Knowing Your Audience: Domestic Coalitions and Justifications for Military Intervention1

Sarah Maxey Post-Doctoral Fellow, Perry World House

University of Pennsylvania smaxey@upenn.edu

Abstract: Conventional wisdom assumes the U.S. public rallies in response to national security threats and reacts uniformly to military action. Why, then, do presidents consistently employ humanitarian justifications for interventions best explained in terms of national security? Disaggregating the public’s foreign policy beliefs, I argue that humanitarian justifications are necessary to build a domestic coalition of support that includes cooperative internationalists—the most likely opponents of intervention and key target audience for presidential appeals. Content analysis and an original dataset of U.S. presidents’ justifications for interventions from 1990 to 2013 reveal that humanitarian claims are prevalent across the post-Cold War period, but presidents exercise discretion in their emphasis of these appeals. Survey experiments demonstrate that the preferences of cooperative internationalists incentivize and constrain humanitarian rhetoric. The results suggest that the composition of domestic support matters as much as the magnitude and identify groups with the leverage to facilitate or constrain intervention.

1 This project was supported by a National Science Foundation Doctoral Dissertation Research Improvement Grant, no. 1559741.

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In September 2013, after establishing the use of chemical weapons as a red line for U.S.

involvement, President Barack Obama addressed the nation to make the case for military action

against Syria. Intervention was necessary, Obama argued, because “Assad’s government gassed

to death over a thousand people, including hundreds of children” (Obama 2013). Despite the

clear evidence of attacks on civilians, humanitarian appeals—defined as references to the

protection or welfare of foreign civilians—failed to mobilize support for military action and

Obama eventually pursued diplomatic alternatives instead (Koh 2016, 999). One year later, in

September 2014, Obama again made the case for military action in Syria, this time to combat the

growing threat posed by the Islamic State of Iraq and the Levant (ISIL). This address focused on

“what the United States will do with our friends and allies to degrade and ultimately destroy the

terrorist group” (Obama 2014). In contrast to the 2013 response, the prospect of a terrorist threat

successfully mobilized public support. Polls conducted immediately after Obama’s speech

reported that 53 percent of respondents approved of his planned military campaign (Pew 2014a).

However, Obama also continued to justify action against ISIL in humanitarian terms. In his 2014

address, prior to mentioning the threat of terrorism, Obama first outlined the threat ISIL posed to

the people of Iraq and Syria, asserting, “In a region that has known so much bloodshed, these

terrorists are unique in their brutality. They execute captured prisoners. They kill children. They

enslave, rape, and force women into marriage. They threatened a religious minority with

genocide” (Obama 2014). Given the ineffectiveness of humanitarian justifications in 2013, why

did Obama continue to employ them at the risk of diluting the terrorism narrative?

Obama’s rhetoric towards Syria is not unique. My analysis of national addresses reveals

that U.S. presidents have used humanitarian justifications in every military intervention of the

past 25 years. However, presidents also appear constrained in their emphasis of humanitarian

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claims, taking care to use these justifications as supplementary explanations in security

interventions. Combined, this widespread use and limited emphasis of humanitarian appeals

highlights unanswered questions about the strategies presidents use to justify interventions and

the conditions under which they effectively bolster public support.

Accounts of domestic attitudes towards military action implicitly assume the public

responds to information about intervention in a uniform way (Gartner and Segura 1998; Gelpi,

Feaver, and Reifler 2009; Geys 2010; Jentleson 1992; Lipset 1988). However, heterogeneity in

the domestic audience makes the support of some individuals more likely and important than

others. The pattern of humanitarian justifications highlights the influence of this heterogeneity on

when and how presidents can mobilize support for intervention—unless humanitarian claims

persuade additional constituencies, presidents have no reason to risk diluting otherwise popular

security narratives. To better understand the target audience for White House communications

and the role that humanitarian justifications play in contemporary interventions, I ask: Why do

presidents consistently use humanitarian justifications in popular, security-driven interventions?

Under what conditions do humanitarian claims bolster support for military action?

This article explains presidents’ justification strategies as a function of the composition of

potential coalitions of domestic support. I argue that the public’s underlying foreign policy

beliefs systematically influence the justifications individuals find most persuasive and whether

they are willing to actively oppose intervention. The public’s heterogeneous preferences create

incentives for presidents to use humanitarian claims widely, but constrain their emphasis of these

appeals in security interventions. Content analysis and an original dataset of justifications for

U.S. interventions from 1990 to 2013 verify that presidents’ speeches follow this pattern.

Drawing on studies of political psychology and public opinion, I then use data from the Chicago

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Council on Global Affairs surveys to show that stable coalitions must maintain the support of

militant internationalists while building support among cooperative internationalists. Cooperative

internationalists possess a unique combination of traits—skepticism towards security goals,

willingness to actively oppose intervention, and political engagement—that make them a critical

target audience for justifications. Persuading these individuals tips the domestic balance towards

support and away from politically costly opposition. Evidence from survey experiments confirms

that cooperative internationalists possess these traits and respond most strongly to humanitarian,

rather than security justifications. The importance of persuading these individuals explains the

utility of humanitarian appeals in contemporary interventions.

This argument has implications for two broader questions that contribute to the

understanding of U.S. foreign policy: What is required to effectively justify military action to the

U.S. public? Whose support is necessary to facilitate intervention? The findings suggest that the

composition of the domestic coalition—i.e., who supports intervention—matters as much as the

magnitude of support and identify the group with the most leverage to facilitate or constrain

military action.

The Pattern of Humanitarian Justifications

The first step towards evaluating whether humanitarian justifications help build domestic

coalitions is to illustrate the pattern of humanitarian appeals. This section employs content

analysis of all national addresses that referenced a U.S. military intervention between 1990 and

2013 to examine how often presidents used and emphasized humanitarian claims in both

humanitarian and security interventions.

Justifications are the public and overt rationale leaders use to convince their publics that

intervention is legitimate, necessary, and worthy of support. Regardless of the primary

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motivation for action, presidents can choose to justify interventions in terms of security and/or

humanitarian concerns.2 Security justifications reference threats to the safety of the domestic

population or U.S. national interests. These justifications establish the benefits of the

intervention for the U.S.3 By contrast, humanitarian justifications refer to the welfare or

protection of foreign civilians and establish how intervention will benefit individuals in the target

state. This analysis focuses on U.S. president’s humanitarian justifications for interventions from

1990 to 2013. Limiting the analysis to the post-Cold War period holds constant the feasibility of

humanitarian justifications as a primary rationale for action (Finnemore 1996; Wheeler 2000).

In this context, military interventions are the deployment of combat troops across

international borders with the purpose of engaging in coercive action, lasting at least one week.4

The operation must last at least one week because presidents are less likely to be held

accountable for non-sustained uses of military force and may justify these actions differently, if

at all. By this standard, the U.S. participated in eight interventions between 1990 and 2013, four

of which pursued primarily security objectives and four of which were humanitarian

interventions. While interventions contain multiple, complex goals, I classify the intervention as

primarily humanitarian or security-driven based on Jentleson and Britton’s (1998) description of

principle policy objectives. Security interventions include: the Gulf War (1991), Haiti (1994),

Afghanistan (2001-14), and Iraq (2003-10). Primarily humanitarian interventions are: Somalia

(1992-93), Bosnia (1994-95), Kosovo (1999), and Libya (2011). All eight cases include

2 Neither scholars nor the public can directly observe leaders’ true motivations for military action. I follow Krebs and Jackson (2007, 42), who argue that public justifications are both observable and the most relevant unit of analysis for understanding how the public perceives military action. 3 See appendix for analysis of security justifications. 4 This definition is consistent with the standard account in studies such as: Finnemore (2003, 9–10), Kreps (2011, 15), and Saunders (2011, 21).

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humanitarian justifications, indicating these claims are not specific to the type of intervention or

rhetorical style of individual presidents.5

From this list of interventions, I used the Public Papers of the Presidents database to

collect all national addresses that mentioned the relevant target state.6 National addresses include

any prepared statement given by the president in an official capacity that either: 1) were given

from the White House, or 2) explicitly identified the nation as the audience. From these national

addresses, I randomly sampled five speeches from each year to read and code justifications for

intervention. Based on this coding, I created a dictionary of humanitarian justifications, searched

a second random sample of speeches for their occurrence, and calculated the rate at which each

term correctly identified a reference to protecting foreign civilians.7 I then imported the

dictionary into Yoshikoder (Lowe 2015) and applied it to all speeches to calculate the number of

times justifications appear in each address.8 This approach follows Krebs’ (2015, 301)

suggestions for mitigating concerns about instability in political communication over time by

“analyzing a narrower range of texts—from a single or relatively homogeneous set of speakers,

from a relatively short time span, from a single country—and by generating search-terms and

coding rules based on a context-sensitive reading of select tests and secondary literature.” The

resulting dataset captures the number of justifications used in each of the 602 speeches

addressing an intervention.

5 See the appendix for examples of the humanitarian justifications used in each case. 6 I collected speeches beginning with the president’s first threat of coercive action for the relevant conflict. See the appendix for an analysis that includes all potential interventions, regardless of whether the conflict ended in military action. 7 See appendix for the complete dictionary and rates of correct identification associated with each term. The tradeoff here is between avoiding phrases that do not reflect humanitarian justifications and omitting relevant justifications by using dictionaries that are too narrow. 8 I followed the same process to capture security justifications. See the appendix for the dictionary of security justifications, as well as a discussion of why these categories are exhaustive in this context.

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From this justification data, I then created two variables to evaluate the pattern of

humanitarian claims across interventions: use and emphasis. Use is a binary measure that takes

the value of one if the given speech includes at least one humanitarian justification and zero

otherwise. Emphasis captures the relative prominence of humanitarian justifications.9 It was

calculated by dividing the number of humanitarian justifications by the total number of

justifications in each speech.

Table 1 summarizes the use and emphasis of humanitarian justifications in the eight

interventions outlined above. Humanitarian appeals were prevalent in both humanitarian and

security-driven interventions, appearing in the majority of speeches regardless of the intervention

type. However, presidents did differentiate between intervention types in their emphasis of

humanitarian claims, using these appeals as only about a quarter of their justifications in

speeches addressing security interventions compared to over half of the justifications for

humanitarian interventions. Given that humanitarian appeals bolster public support (Boettcher

2004; Kreps and Maxey 2017) and are feasible in security interventions, why do presidents limit

their emphasis? In the following section, I demonstrate that existing theories of public attitudes

towards military action leave this question unanswered and contend that the pattern reflects the

domestic coalition presidents must build to generate sustainable support for intervention.

9 Compared to security justifications.

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Table 1. Use and Emphasis of Humanitarian Justifications Humanitarian

Interventions Security

Interventions Used in Speech 86

(72%)

276 (57%)

Emphasis

55%

28%

Total Speeches 119 483 Note: Emphasis reports average percentage of claims that were humanitarian in speeches addressing each intervention type.

Why Justifications Matter

U.S. presidents’ efforts to justify military action stem from their democratic

accountability to citizens who pay the costs of war and can vote leaders and their parties out of

office. Presidents who pursue intervention without the support of the public risk political

punishment, either at the polls or through tightened institutional constraints that make it difficult

to pursue their political agendas (Gelpi, Feaver, and Reifler 2009; Larson 1996; Reiter and Stam

2002; Tomz and Weeks 2013). As a result, leaders develop frames for intervention to control the

flow of information and pay careful attention to public perceptions of military action (Druckman

and Jacobs 2015; Jacobs and Shapiro 2000; Western 2005, 17). Explaining the importance of

public support for policy decisions, Edwards (2000, 48) notes, “Leading the public—changing

opinions and mobilizing citizens into action—is perhaps the ultimate resource of the democratic

political leader. It is difficult for others who hold power to deny the legitimate demands of a

president with popular support.” With the public on their side, presidents undercut the incentives

of Congress and other elites to oppose the intervention, increasing their leeway to take action

(Kernell 1997; Schultz 2003).

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In addition to bolstering support, presidents also have an incentive to prevent the

formation of a vocal and politically costly opposition. Mobilized opposition raises questions

about the legitimacy of a president’s foreign policy and exacerbates the erosion of support over

time (Baum and Groeling 2010; Kam and Ramos 2008). It also encourages elites who disagree

with the president to voice their dissent and take action to block the intervention. In this context,

the goals of presidents’ justifications for military action are two-fold: 1) to generate sufficient

support to facilitate intervention, and 2) to limit the intensity of dissent so that even individuals

who oppose intervention are not compelled to take to the streets.

While media coverage and partisan discourse also influence attitudes towards military

action (Berinsky 2007; Brody 1991; Groeling and Baum 2008), presidents’ first-mover and

information advantages on matters of foreign policy make their justifications particularly

relevant to the public’s perceptions of intervention (Baum and Groeling 2010). In his capacity as

Commander in Chief, the president introduces the prospect of military action and offers the

initial explanation for intervention, setting the terms of the debate that follows. For example,

Kull, Ramsay, and Lewis (2003, 571) find evidence that “In the run-up to the war with Iraq and

in the postwar period, a significant portion of the American public has held a number of

misperceptions relevant to the rationales for going to war with Iraq.” The persistence of beliefs in

Bush’s initial rationale for action—that Saddam Hussein had weapons of mass destruction—and

their continued correlation with support for military action (Kull, Ramsay, and Lewis 2003, 579)

demonstrate that presidents’ justifications can influence public attitudes in the long-run, even in

the face of elite dissent and contradictory information. Examining presidents’ justification

strategies thus sheds light on a central part of the process through which public support is

mobilized to facilitate intervention (Krebs 2015, 15).

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In addition to focusing on presidents’ justifications, I also consider the U.S. public as the

primary audience for humanitarian claims. Instead, these justifications could target international

audiences by framing intervention in terms of internationally held standards of appropriate

behavior (Finnemore 1996, 159). However, allies’ support is not driven by international public

opinion (Kreps 2010) and leaders make strategic choices about when gaining international

approval is worth the cost (Chapman 2011, 6). Additionally, international opponents of

intervention are often unconvinced by humanitarian appeals. For example, Russia, China, and

India opposed the humanitarian rationale for NATO actions in Kosovo (Wheeler 2004, 43) and,

more recently, Russia and China publicly rebuked the U.S. and NATO for using humanitarian

statements to gain support for intervention in Libya (Foust 2012). International approval is

therefore neither consistently sought nor most effectively obtained with humanitarian

justifications. U.S. presidents’ consistent use of humanitarian claims is thus unlikely to be

primarily directed at international audiences.

Attitudes Towards Justifications

Theories of public opinion offer two alternative accounts of how the public responds to

information about intervention. The first contends that, unlike leaders who understand the

complexities of foreign policy, the public is inattentive, impulsive, and emotional (P. E.

Converse 1964; Holsti 1992, 440; Lipset 1988; Morgenthau 1951). From this perspective,

humanitarian appeals have widespread appeal because the national interest is “best served by the

very Realpolitik that ordinary citizens find abhorrent,” and “policymakers need to either brace

themselves for political backlash, or camouflage their policies in anti-realist rhetoric” (Kertzer

and McGraw 2012, 245). This account is consistent with the presence of humanitarian

justifications in both humanitarian and security interventions. However, if humanitarian appeals

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primarily “camouflage” security concerns that the public neither understands nor supports,

presidents should also emphasize humanitarian claims at least as often as security explanations.

Therefore, this approach does not explain presidents’ lower emphasis of humanitarian

justifications in security interventions.

A second camp presents evidence that the public is instead prudent in its approach to

foreign policy, weighing the costs of intervention relative to the likelihood of success and the

legitimacy of the objectives (Eichenberg 2005; Gelpi, Feaver, and Reifler 2009; Jentleson 1992;

Jentleson and Britton 1998). Unless they provide new information about these factors, additional

justifications are unlikely to influence the public’s assessment of the conflict. This account is

consistent with the limited emphasis of humanitarian appeals in security cases—because the

costs and legitimacy of these interventions are primarily driven by security concerns,

humanitarian justifications will provide little relevant information to help make the president’s

case and may actually raise concerns that the objectives include imprudent and unpopular

internal political change (Jentleson and Britton 1998). However, from this perspective, presidents

also have few incentives to muddy the narrative of popular security interventions by adding any

humanitarian appeals.10 As a result, it does not explain the prevalence of humanitarian

explanations in security interventions. Therefore, neither existing account of how the public

responds to information about military action is consistent with the full pattern of humanitarian

justifications.

Building Domestic Coalitions

Existing accounts of public attitudes towards military action are united by the implicit

assumption that there is a single U.S. public that assesses intervention in a uniform way.

10 See appendix for evidence that humanitarian claims increase expectations of humanitarian outcomes, making their use in popular security interventions costly.

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Analyses of partisanship and gender reveal that some individuals are more likely to support

intervention than others (Berinsky 2007; Eichenberg 2016), but do not consider the relative

importance of different groups for building domestic coalitions. By contrast, scholarship on

foreign policy beliefs demonstrates that individuals respond to foreign policy decisions based on

their underlying preferences for when and how the U.S. should engage in international affairs

(Chanley 1999; Kertzer et al. 2014; Mandelbaum and Schneider 1979; Wittkopf 1986, 1994;

Wittkopf and Maggiotto 1983). Connecting communication strategies to foreign policy beliefs, it

becomes possible to identify the groups presidents must persuade to generate stable support for

military action and the justifications most likely to resonate with key individuals. The

composition of this domestic coalition of support accounts for the pattern of humanitarian

justifications.

Disaggregating the Domestic Audience

The U.S. public can be divided into three categories of foreign policy beliefs,

summarized in Figure 1: militant internationalists, cooperative internationalists, and isolationists

(Hurwitz and Peffley 1987; Kertzer 2013; Kertzer et al. 2014; Mandelbaum and Schneider 1979;

Wittkopf 1990, 1994). First, individuals are positioned along an isolationist-internationalist

dimension based on whether they believe the U.S. should play an active role in the world.

Isolationists oppose active engagement, while internationalists believe the U.S. should

participate in international affairs.

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Figure 1. Foreign Policy Beliefs

Preferred Form of U.S. Engagement

Military Cooperative

Active U.S. role in world affairs?

Yes Militant Internationalists

Cooperative Internationalists

No Isolationists

Internationalists are then divided along a second cooperative-militant dimension based on

what form U.S. engagement should take (Kertzer et al. 2014).11 Militant internationalists believe

national security goals are the most important foreign policy objectives and view military force

as the central tool for achieving these goals (Schneider 1983, 40). As a result, militant

internationalists are inclined to support interventions—both security and humanitarian—as an

effective way to solve international problems. Alternatively, cooperative internationalists favor

humanitarian and multilateral foreign policy goals and prefer to focus on global problems such as

the scarcity of natural resources, pollution, and international economic inequality rather than

maximizing U.S. military strength (Kertzer et al. 2014, 826; Schneider 1983, 40). As a result,

they are less likely to view military force as an effective tool of foreign policy (Mandelbaum and

Schneider 1979, 38).12

The Target Audience for Justifications

Building on individuals’ underlying foreign policy beliefs, I develop theoretical

expectations for how isolationists, militant internationalists, and cooperative internationalists

11 The defining characteristic of isolationists is their lack of support for engagement in international affairs. Because they are not easily convinced to support action for security or humanitarian objectives, I analyze this category in the aggregate. 12 Mandelbaum and Schneider (1979), as well as Schneider (1983), refer to these categories as liberal and conservative internationalists, divided along the same dimensions. Following Kertzer et al. ( 2014) and Wittkopf (1990), I use the terms cooperative and militant internationalists to avoid confusion with partisan ideology.

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respond to justifications for military action. Together, these expectations clarify which

individuals can be persuaded to support military action, represent a politically costly source of

opposition, and are thus an efficient target audience for the president’s message.

In addition to favoring disengagement with international affairs, isolationists are

themselves relatively disengaged from the political process (Schneider 1983, 41–42; Wittkopf

1986, 435). These individuals are “not so much opposed as they are nonsupportive” of

involvement in international affairs, will only approve of military action when there is an

immediate threat to U.S. interests, and demand “swift, decisive action but not long-term

involvement” (Schneider 1983, 42-43). Because they offer only short-term support for

immediate threats and their lack of engagement makes them an unlikely source of costly

opposition, I contend that isolationists are an inefficient target audience for presidents’

justifications—they will be hard to persuade and unlikely to sustain support for military action,

regardless of the justifications used. These characteristics generate the following hypotheses:

H1a: Isolationists have the lowest level of political engagement.

H1b: Isolationists offer low levels of support for all categories of justifications.

Alternatively, internationalists endorse participation in international affairs and can be

persuaded to offer long-term support for interventions. They are also more likely to be educated

and politically engaged (Kertzer 2013, 237; Wittkopf 1987, 134). This level of political

engagement makes both militant and cooperative internationalists a credible source of costly

opposition. Combined, the possibility of persuading internationalists and the risk of opposition

make them potential targets for president’s justifications.

Further disaggregating internationalists, I expect militant internationalists to be consistent

supporters of intervention because they believe in the active pursuit of security objectives and the

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efficacy of military force as a means of engagement. These individuals respond positively to

security justifications, which introduce a threat to the U.S. that can be addressed through military

action. However, their baseline belief that military force effectively solves international

problems, including humanitarian crises, means that militant internationalists also support

humanitarian justifications.13 While militant internationalists are a necessary component of

domestic coalitions of support, presidents will not have to work hard to persuade these

individuals.

H2a: Militant internationalists are more politically engaged than isolationists.

H2b: Militant internationalists offer high levels of support for all types of justifications.

By contrast, I contend that cooperative internationalists are the equivalent of swing voters

in potential coalitions of support. These individuals believe the U.S. should help solve

international problems and can be convinced that intervention is necessary. However, they

prioritize humanitarian and multilateral goals and are skeptical of both military force and

national security objectives, making security justifications less persuasive. Instead, I expect

cooperative internationalists to respond to humanitarian justifications, which shift the focus of

intervention from the matters of realpolitik associated with security claims to what Drezner

(2008, 54) refers to as “internationalist policy priorities,” including “the protection of human

rights, democracy promotion, or the strengthening of multilateral institutions.” Their potential

opposition and skepticism towards military action make cooperative internationalists a key target

for presidential communications in general and humanitarian justifications in particular, in line

with the following hypotheses:

13 However, these individuals may be less willing to support long or costly humanitarian interventions. Testing the effects of foreign policy beliefs over the course of an intervention is an important question that is beyond the scope of this article.

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H3a: Cooperative internationalists are more politically engaged than isolationists.

H3b: Cooperative internationalists offer higher support for justifications that include humanitarian appeals than for security justifications.

Presidents should thus have an incentive to emphasize humanitarian claims as often as

possible because they appeal to militant and cooperative internationalists. However, because

cooperative internationalists are skeptical of security objectives and politically engaged, I also

expect them to recognize and respond negatively to the misuse of humanitarian appeals as a

cover for security goals. The implication for leaders’ justification strategies is that more is not

always better when it comes to humanitarian appeals. Humanitarian claims can help build a

coalition of support for security interventions, but their benefits are only realized if security

justifications remain prominent.

H4: Cooperative internationalists offer lower support for humanitarian justifications when they appear insincere.

The Distribution of Foreign Policy Beliefs

In their account of U.S. foreign policy beliefs during the Cold War, Mandelbaum and

Schneider (1979, 41-42) used factor analysis of data from Chicago Council surveys to uncover

the foreign policy goals associated with the different types of internationalism. Their findings

revealed that a coalition of internationalists was necessary to achieve a consensus on foreign

policy decisions (Mandelbaum and Schneider 1979, 48). In the more than 30 years since the

initial study, the distribution of U.S. foreign policy beliefs has changed, but the need for a

coalition of cooperative and militant internationalists remains. Drawing on data from 13 waves

of the Chicago Council surveys, 1974-2015, Figure 2 illustrates changes in the average

percentage of respondents who listed militant or cooperative internationalist goals as “very

important,” as well as the percentage of respondents who agreed with the isolationist sentiment

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that it “will be best for the future of the country if we stay out of world affairs.”14 Not all policy

options were consistently included in the survey, but Figure 2 reports the average for all policies

from Mandelbaum and Schneider’s list that were present in the given year. Average support for

militant internationalist policies ranges from a maximum of 46 percent in 1982 to a minimum of

only 14 percent in 2012. Cooperative internationalist policies received a consistently higher

average level of support that ranges from a peak of 61 percent when the survey was first

conducted in 1974 to a low of 43 percent in 2001.

Figure 2. Importance of Cooperative, Militant, Isolationist Policies, 1974-2015

These averages do not capture the relative salience of individuals’ militant or cooperative

beliefs and are sensitive to the questions included in a given year, but over-time variation

highlights a key point about potential domestic coalitions of support. While support for policies

waxes and wanes, at no point could a consensus be reached without the approval of some

individuals who support cooperative internationalist policies. Persuading individuals with

14 A complete list of the policies associated with cooperative and militant internationalism, as well as responses to individual items by year is included in the appendix.

1020

3040

5060

1970 1980 1990 2000 2010Year

% Respondents Cooperative % Respondents Militant% Respondents Isolationist

% Respondents Who Think Cooperative, Militant, Isolationist Policies Very Important

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cooperative internationalist beliefs is therefore critical to building a domestic coalition that

includes and can sustain a majority of the public support for intervention. The position and

preferences of cooperative internationalists within the domestic coalition account for the

widespread use and limited emphasis of humanitarian justifications.

Research Design

To test the implications of the domestic coalition argument for each category of foreign

policy beliefs, I designed two survey experiments that randomize the content and the sincerity of

justifications for intervention. The experiments gauge the extent to which individuals’ foreign

policy beliefs influence: 1) their willingness to actively oppose intervention, 2) the types of

justifications they find most persuasive, and 3) their sensitivity to the misuse of humanitarian

appeals. An experimental approach is necessary in this context because, unlike observational

studies, it controls the information respondents receive about a potential intervention and

disentangles support for justifications from respondents’ approval of the current president.

Foreign Policy Beliefs and Support

In both experiments respondents received the same set of questions designed to measure

two key variables: underlying foreign policy beliefs and support for the hypothetical

intervention. To ensure that the foreign policy belief indicator captured individuals’ underlying

preferences and was not primed by exposure to humanitarian justifications, respondents

answered this question alongside demographic items before receiving the treatment.15 The

indicator divided respondents into three categories—cooperative internationalists, militant

15 I took three steps to mitigate the risk that the preliminary questions then primed responses to the treatment: 1) the foreign policy belief indicators did not reference intervention or specific scenarios to avoid drawing a connection between the question and the treatment that followed, 2) the foreign policy belief question was presented as part of a battery of other demographic questions to reduce the risk that it would stand out to respondents, and 3) the demographic questions asked respondents about non-political issues such as education level to avoid priming other relevant considerations. Political demographic questions such as party identity were included in a separate section at the end of the survey.

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internationalists, and isolationists—based on the measures validated by Kertzer et al. (2014,

Appendix) and the Chicago Council survey questions used by Mandelbaum and Schneider

(1979, 42–43). These studies rely on a battery of questions to sort respondents into categories of

internationalism or isolationism. However, in this experimental context, including an extended

battery of questions alongside the treatment has significant shortcomings. First, presenting

respondents with multiple questions about foreign policy can prime their approach to

intervention and bias responses to the treatment scenario (J. M. Converse and Presser 1986, 39–

40). Second, requiring respondents to answer a long series of questions, before or after the

treatment scenario, increases the risk that they will satisfice or give non-meaningful responses to

either the treatment or the foreign policy questions (McDermott 2011, 33).

Instead, I used the items from Kertzer et al.’s (2014, Appendix) index and the Chicago

Council measure of isolationism to develop three statements that reflect primarily cooperative

internationalist, militant internationalist, or isolationist beliefs. Respondents then selected the

statement they believed “best reflects the role the United States should play in the world.”

Individuals were coded as cooperative internationalists if they thought “It is essential for the

United States to work with other nations to solve problems such as overpopulation, hunger, and

pollution.” Respondents were categorized as militant internationalists if they chose “It is

important for the United States to maintain a strong military to ensure world peace.” Isolationists

selected “It is best for the future of the United States if we stay out of world affairs.” Because

foreign policy beliefs exist along a spectrum and this question forces individuals into a single

category, responses should be interpreted as the individual’s predominant foreign policy

orientation. While less fine-grained than the conventional measures, this approach provides a

hard test of the domestic coalition expectations—individuals coded as cooperative

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internationalists in this context may also hold views consistent with militant internationalism or

isolationism. Such individuals should be more likely to respond to security justifications and

insincere humanitarian justifications than the argument anticipates.

After the treatment scenario, the surveys also probed participants’ support for the

proposed intervention. The surveys then gauged respondents’ willingness to take action to

express their opinion and asked additional demographic questions, including a manipulation

check. These questions are discussed in detail in the following sections.

Experiment One

Experiment one gauged how individuals respond to justifications based on their foreign

policy beliefs. It randomly assigned respondents to scenarios in which a hypothetical president

advocated for intervention using one of three categories of justifications: humanitarian, security,

or a combination of security and humanitarian claims. The scenarios mirrored the rhetoric

presidents used to justify interventions in the Gulf War, Bosnia, Afghanistan, Iraq, and Libya.

Drawing on rhetoric used in recent interventions increases the external validity of the treatments

by helping to ensure that they reflect contemporary rhetorical conventions. Additionally,

combining the claims of Democratic and Republican presidents makes it more difficult for

respondents to associate the justification with a particular political party.

In each condition respondents were told that “Over the last few months, a violent conflict

has developed in the country of Numar” and that they were reading excerpts from a hypothetical

president’s address to the nation about this conflict. In the humanitarian condition, the president

called for intervention because the foreign regime posed a threat to “its own civilians, including

innocent women and children” and had “killed thousands of its own people and directly targeted

civilians.” In the security condition, the president evoked a foreign policy restraint scenario akin

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to the Gulf War (Jentleson 1992), calling for action against a foreign regime that posed a threat

to “the security of the United States, including the American people” because it had “invaded its

neighboring state and is a threat to the United States.” In the combined condition, intervention

was necessary because the foreign regime presented a threat to “its own civilians and to the

security of the United States. It has invaded its neighboring state and killed thousands of its own

people.”16 Following the president’s statement, respondents were told that experts agreed with

the president’s justifications for intervention and bullet points summarized the scenario.17

Experiment one was fielded to a national sample of 834 U.S. adults through Survey

Sampling International (SSI) on July 14-28, 2017. The analysis presented in the following

section includes the 497 participants who passed the manipulation check (Mutz and Pemantle

2015; Oppenheimer, Meyvis, and Davidnko 2009).18 The manipulation check was included at the

end of the survey and asked respondents: “To the best of your recollection, in the previous

section, what reasons did the hypothetical president give for taking military action in Numar?”

The order of the response options was randomized and included: only humanitarian goals, only

security goals, both humanitarian and security goals, and neither humanitarian nor security goals.

This approach is in line with the standard promoted by Mutz and Pemantle (2015, 195), who

explain that these checks are necessary, especially in the context of online survey experiments, to

evaluate “whether the treatment manipulated the independent variable as intended. Subjects may

doubt the veracity of information they are given, or they may not find the treatment as

threatening, anxiety-inducing, or a counter-attitudinal (or whatever the treatment happens to be)

16 See the appendix for the complete scenario. The design is loosely based on Tomz and Weeks (2013) and Trager and Vavreck (2011). 17 Including expert information standardizes the treatment conditions with the second experiment and helps ensure that trust in the presidency does not confound the results. See the appendix for a follow-up experiment that shows expert agreement does not significantly influence support for the intervention. 18 See the appendix for results including respondents who failed the check.

22

as the investigator intended.”19 In the context of this experiment, focusing on individuals for

whom the treatment manipulated the independent variable—i.e., the type of justification—as

intended is key because the modal mistake was to report reading both humanitarian and security

justifications.20 Because individuals who failed the check assumed humanitarian justifications

where there were none, excluding these respondents from the analysis is necessary to interpret

the difference in support between the security and combined condition as the effect of adding a

humanitarian justification to a security explanation.

Experiment Two

Experiment two varied both the content and the sincerity of justifications to investigate

whether foreign policy beliefs influence reactions to the misuse of humanitarian claims. The

humanitarian condition for this experiment was consistent with experiment one; however, the

security and combined conditions introduced the prospect of a terrorist threat rather than a

foreign policy restraint scenario. In the terrorism condition, the president called for intervention

because the foreign regime posed a threat to “the security of the United States, including the

American people” and had “created a safe haven for terrorists and threatened the United States.”

In the combined conditions, the president claimed military action was necessary because the

foreign regime presented a threat to “its own civilians and to the security of the United States. It

has created a safe haven for terrorists and killed thousands of its own people.”

Following the president’s statement, respondents were told that a majority of experts

either publicly agreed with or disputed the president’s reasons for intervention and that the real

motivation for U.S. action was to protect U.S. security or the foreign state’s civilians. Bullet

19 Notably, manipulation checks are distinct from “screeners” because “Rather than address whether a subject was exposed to the treatment, manipulation checks are designed to assess whether the treatment successfully induced variance in the independent variable” (Mutz and Pemantle 2015, 196). 20 See the appendix for results of the manipulation check.

23

points then summarized the explanations offered by the president and experts. Combined,

variation in the content and sincerity of justifications creates the seven experimental conditions

outlined in Table 2.21

Table 2. Experiment Two Treatment Conditions (Justifications/Facts) Humanitarian Security Combined

Sincere Humanitarian/ Humanitarian

Security/ Security

Security and Humanitarian/ Security and Humanitarian

Insincere Humanitarian/ Security

Security/ Humanitarian

Security and Humanitarian/ Security

Security and Humanitarian/ Humanitarian

Experiment two was fielded to a sample 1,055 U.S. adults using Amazon’s Mechanical

Turk (MTurk) from July 14-23, 2016. As before, the analysis that follows is limited to the 792

respondents who passed the manipulation check and the results for all respondents are reported

in the appendix. MTurk samples are not nationally representative (Berinsky, Huber, and Lenz

2012). As the demographic information included in the appendix shows, respondents were more

educated, liberal, and likely to be female than the general population. However, in the context of

the domestic coalition argument, the demographics of the MTurk sample are an advantage—the

same characteristics that are over-represented in MTurk samples correlate with cooperative

internationalist values (Mandelbaum and Schneider 1979, 43), helping to ensure that a sufficient

number of cooperative internationalists are present to facilitate the subgroup analysis and detect

meaningful differences in this group’s response to humanitarian justifications. Additionally, the

appendix replicates the key findings from experiment one, increasing confidence that unobserved

differences in the MTurk sample do not systematically skew responses in the context of this

study.

21 See appendix for the scenario text.

24

Experiment One Results

Costly Opposition

The domestic coalition argument contends that cooperative internationalists are a key

constituency in the mobilization of support for intervention. Unlike isolationists—who oppose

intervention but are unlikely to take action to express their dissent—or militant

internationalists—who are unlikely to oppose intervention in the first place—cooperative

internationalists are both politically engaged and skeptical of military action, making them the

most likely source of costly opposition. These expectations are formalized in hypotheses 1a, 2a,

and 3a, above. The first experiment gauged respondents’ political engagement in two ways: 1) by

asking what actions they would take to express their opinion, and 2) by probing whether they

voted in the previous presidential election.

First, respondents were presented with a list of activities and asked to select which they

would be willing to take to show their support or opposition to the intervention.22 I then used the

total number of actions selected to create an additive index of potential opposition than ranged

from zero to five. Table 3 shows that cooperative internationalists were willing to take the

highest number of actions. On average, individuals with cooperative internationalist values were

willing to take 1.43 actions to express their opinion about military action, compared to 1.10

actions for militant internationalists and 1.27 actions among isolationists. The difference between

cooperative and militant internationalists is statistically significant. Contrary to hypotheses 1a

22 The order of response options was randomized and included: 1) use social media to express my opinion about the military action, 2) sign a petition about the military action, 3) write a letter to the editor of a newspaper expressing my opinion about the military action, 4) contact my Member of Congress to express my opinion about the military action, 5) participate in a rally about the military action, and 6) none of the above.

25

and 2a, militant internationalists selected a lower number of actions than isolationists, but this

difference is not statistically significant (p=0.3000).23

Table 3. Measures of Political Engagement Index Score Voted Cooperative Internationalists 1.43

(0.08)

0.77 (0.03)

Militant Internationalists 1.10*

(0.08)

0.72 (0.04)

Isolationists 1.27 (0.16)

0.60* (0.06)

N 497 496 Table reports the results of two-tailed comparison of means tests (index score) and tests of proportions (voted) that compared each category of foreign policy beliefs to the cooperative internationalist baseline. Standard errors reported in parentheses. *p<0.05.

The potential for politically costly opposition from cooperative internationalists becomes

more credible when combined with evidence that they are also more prone to express their

opinions at the polls than isolationists. 77 percent of cooperative internationalists reported voting

in the 2016 presidential election compared to 60 percent of isolationists. In this case, there is

limited support for hypothesis 2a, as militant internationalists also reported voting in higher

numbers than isolationists (p=0.0738). While reported voting is likely inflated, this measure

assesses relative differences between the groups. Combined, these results support the domestic

coalition argument’s expectation (hypothesis 3a) that persuading cooperative internationalists is

important because they are engaged and willing to express their dissent.

23 See appendix for a breakdown of respondents’ willingness to take each action in the index.

26

Persuasive Justifications

The domestic coalition argument also expects cooperative internationalists to be a key

target audience for the president’s message because they do not offer comparable support for all

justifications—these are the individuals for whom the content of the president’s justifications

matters. By contrast, militant internationalists are expected to offer high and comparable levels

of support for all justifications, while isolationists offer low levels of support for intervention

regardless of the explanation. These expectations are outlined in hypotheses 1b, 2b, and 3b,

above.

As Figure 3 illustrates, humanitarian justifications alone generate high and statistically

indistinguishable levels of support from cooperative and militant internationalists. Humanitarian

claims therefore appear well-suited to mobilizing an internationalist coalition of support.

Isolationists offer significantly lower support and are not persuaded by humanitarian appeals.

Figure 3. Support for Humanitarian Justifications

27

The question then becomes whether militant and cooperative internationalists are equally

responsive to all types of justifications. Table 4 compares support for security justifications and

the combined justification category to demonstrate that, as expected, cooperative internationalists

are the only group whose support increased significantly when a humanitarian claim was added

to a security explanation. In the security condition, cooperative internationalists offered

borderline support for intervention, comparable to the support of isolationists and significantly

lower than the support of militant internationalists (p=0.0001). However, when humanitarian

justifications were added to the security explanation, the support of cooperative internationalists

increased by almost 20 percent, placing a strong majority of these individuals in the coalition of

support for intervention.

Table 4. Support for Security and Combined Justifications Security Combined Difference Cooperative Internationalists

0.53 (0.05)

0.72 (0.04)

0.19* (0.07)

Militant Internationalists

0.88 (0.05)

0.83 (0.04)

0.05 (0.07)

Isolationists 0.55 (0.11)

0.44 (0.12)

0.11 (0.16)

N 163 198 Table reports results from two-tailed tests of proportions. Standard errors reported in parentheses. *p<0.05.

The effect of humanitarian claims on cooperative internationalists’ support is particularly

striking given the absence of significant effects among militant internationalists or isolationists.

Militant internationalists offered high levels of support for all justifications and their support did

not change significantly in the combined condition. Alternatively, isolationists offered low levels

28

of support for all justifications. Their support was highest in the security category but declined

when humanitarian claims were added.

Combined, these results provide strong support for the expectations of the domestic

coalition argument. Consistent with hypotheses 1b and 2b, respectively, the results demonstrate

the isolationists offered low levels of support across all categories of justifications, while militant

internationalists were highly supportive of all justifications. In line with hypothesis 3b, the

addition of humanitarian claims had a statistically and substantively significant effect on the

support of cooperative internationalists, who otherwise offered relatively low support for security

justifications. The analysis demonstrates that cooperative internationalists are the only group

significantly and positively influenced by the addition of humanitarian claims. Gaining their

support is the benefit presidents receive for referencing humanitarian claims in security

interventions.

Experiment Two Results

Because humanitarian appeals resonate with all internationalists—compared to the

limited salience of security claims—presidents should have an incentive to highlight these

justifications. Why, then, do presidents limit their emphasis of humanitarian explanations in

security interventions? The domestic coalition argument contends that the same individuals who

make humanitarian justifications necessary also limit their effectiveness. As outlined in

hypothesis 4, I expect cooperative internationalists to respond negatively to evidence that

humanitarian justifications are an insincere cover for security motivations. Experiment two

evaluates these expectations by varying the sincerity of the president’s justifications.

Table 5 reports the differences in support for sincere and insincere claims within each

category of justification. Consistent with hypothesis 4, cooperative internationalists’ support

29

dropped significantly when expert information contradicted the president’s humanitarian appeal.

The reduced support of cooperative internationalists, who are key to building domestic

coalitions, suggests that presidents cannot easily use humanitarian claims as the sole pretext for

security interventions. Support from militant internationalists and isolationists was not

significantly affected by insincere humanitarian justifications.

30

Table 5. Effect of Sincerity on Support Cooperative

Internationalists Militant

Internationalists Isolationists

Humanitarian Sincere 0.71

(0.06) 0.77

(0.08)

0.14 (0.09)

Insincere 0.28 (0.06)

0.64 (0.10)

0.00 (0.00)

Difference 0.43* (0.08)

0.13 (0.12)

0.14 (0.09)

Security Sincere 0.49

(0.06) 0.96

(0.04)

0.37 (0.11)

Insincere 0.35 (0.06)

0.62 (0.10)

0.11 (0.10)

Difference 0.14 (0.08)

0.34* (0.10)

0.26 (0.15)

Combined Sincere 0.66

(0.06) 0.91

(0.05)

0.35 (0.11)

Insincere Humanitarian

0.53 (0.06)

0.88 (0.06)

0.27 (0.09)

Difference 1 0.13 (0.08)

0.03 (0.08)

0.08 (0.14)

Insincere Security

0.56 (0.06)

0.69 (0.09)

0.17 (0.09)

Difference 2 0.10 (0.08)

0.22* (0.10)

0.18 (0.14)

N 479 193 119 Table reports results from two-tailed tests of proportions. Standard errors reported in parentheses. Difference 1 reports difference between sincere combined and insincere humanitarian, difference 2 between sincere combined and insincere security. *p<0.05.

However, Table 5 also implies that the effect of insincere humanitarian justifications is

reduced when these appeals are combined with sincere security claims. Cooperative

31

internationalists did not offer significantly lower support for interventions that combined sincere

security claims with insincere humanitarian justifications. The support of militant

internationalists and isolationists was also not significantly affected by the addition of insincere

humanitarian appeals.

Overall, the results indicate that cooperative internationalists are both significantly

influenced by humanitarian appeals and sensitive to the insincere use of humanitarian

justifications as the sole explanation for military action. However, the support of cooperative

internationalists was not significantly reduced when the president combined insincere

humanitarian claims with sincere security explanations. To maximize the benefits and minimize

the risks of including of humanitarian appeals in security interventions, presidents should use

these justifications as supplements to uncontested security claims. Combined, these findings shed

light on the incentives behind presidents’ prevalent use and limited emphasis of humanitarian

justifications in post-Cold War interventions.

Conclusion

Humanitarian justifications are a central part of presidents’ strategies for bolstering

public support for intervention. Existing accounts assume that the public responds to

justifications in a uniform way and expect the president to use humanitarian claims either

without constraint or primarily in cases of humanitarian intervention. Instead, content analysis of

national addresses indicates that the actual pattern of justifications falls between these two

extremes. Presidents employ humanitarian appeals in the majority of their speeches on

humanitarian and security interventions, but consistently limit the emphasis placed on

humanitarian explanations in security cases. To account for this pattern, the article proposes a

32

domestic coalition argument, asserting that presidents’ justifications are driven by the need to

persuade cooperative internationalists.

Findings from experiment one support the domestic coalition hypotheses and provide

evidence that individuals’ foreign policy beliefs influence their responses to justifications. The

results show that cooperative internationalists are both skeptical of security justifications and the

only group whose support for intervention is significantly influenced by the addition of

humanitarian justifications. Responses also demonstrate that cooperative internationalists are

willing to actively oppose military interventions and are politically engaged. This unique

combination of traits—lower support for security justifications, willingness to oppose

interventions, and political engagement—makes cooperative internationalists a critical target

audience for presidential justifications in general and humanitarian justifications in particular.

The preferences of cooperative internationalists also limit the effectiveness of

humanitarian appeals. Experiment two shows that these individuals are sensitive to the insincere

use of humanitarian claims as the sole explanation for security interventions. However, their

support for intervention does not decline significantly when insincere humanitarian appeals are

combined with sincere security explanations. These findings imply that to maximize the support

of cooperative internationalists, presidents have an incentive to include humanitarian appeals

alongside security justifications but avoid attracting scrutiny by presenting humanitarian

explanations as a secondary rationale for security interventions.

This analysis highlights the role that humanitarian appeals play in generating public

support for the use of force. Contrary to conventional wisdom, the findings imply that national

security justifications are neither the most effective nor the only way to bolster support for

intervention. Individuals also respond to concerns about foreign civilians, even outside of cases

33

of humanitarian intervention. By demonstrating how humanitarian appeals contribute to

domestic support for intervention, the findings help explain why these justifications have

historical precedents long before the evolution of humanitarian intervention norms (Bass 2008).

Additionally, the project speaks to the broader questions of how much public support is

necessary to facilitate intervention and the conditions under which presidents can generate this

support. Disaggregating public opinion based on individuals’ foreign policy beliefs reveals that

not all support is created equal—if the domestic coalition does not include cooperative

internationalists, it will be difficult to sustain and subject to active opposition. Presidents can

build this stable coalition of support when they frame the intervention in terms that appeal to

both cooperative and militant internationalists. However, if presidents attempt to use insincere

humanitarian claims as the sole pretext for security interventions, these justifications will not

generate sufficient public support. Selecting the right combination of justifications thus gives

presidents leeway to pursue military action, but there are limits to the power of humanitarian

rhetoric.

What this analysis cannot determine is whether the pattern of humanitarian justifications

reflects an intentional White House strategy designed to target cooperative internationalists or is

a positive a side effect of decisions driven by other concerns. A full examination of White House

decision-making is beyond the scope of this article. However, in their case studies of internal

polling and White House communications, Druckman and Jacobs (2015, 29) demonstrate that

presidents collect the “most important problem” information necessary to understand

heterogeneity in the public’s foreign policy beliefs: “Starting in earnest with Johnson, the White

House’s political needs drove its collection of data on five categories of public opinion: policy

preferences, issue approval, most important problem, personality traits, and subgroup

34

demographics.” Additionally, preliminary archival evidence from George H.W. Bush’s open

letter to college students during the Gulf War suggests the White House recognized the limits of

humanitarian appeals in security interventions, noting in drafts that “The almost exclusive focus

on human rights arguments is not an accurate reflection of what lies behind our involvement”

(Jackson 1991). A more direct and comprehensive test of presidents’ intent is an important

avenue for future research, but these examples suggest the presidents have the information

necessary to identify and target cooperative internationalists with their communication strategies.

35

References

Bass, Gary. 2008. Freedom’s Battle: The Origins of Humanitarian Intervention. New York: Alfred Knopf.

Baum, Matthew, and Tim Groeling. 2010. “Reality Asserts Itself: Public Opinion on Iraq and the Elasticity of Reality.” International Organization 64: 443–79.

Berinsky, Adam. 2007. “Assuming the Costs of War: Events, Elites, and American Public Support for Military Conflict.” Journal of Politics 69 (4): 975–97.

Berinsky, Adam, Gregory A. Huber, and Gabriel S. Lenz. 2012. “Evaluating Online Labor Markets for Experimental Research: Amazon.com’s Mechanical Turk.” Political Analysis 20 (3): 351–68.

Boettcher, William. 2004. “Military Intervention Decisions Regarding Humanitarian Crises.” Journal of Conflict Resolution 48 (3): 331–55.

Brody, Richard. 1991. Assessing the President: The Media, Elite Opinion, and Public Support. Stanford: Stanford University Press.

Chanley, Virgina A. 1999. “U.S. Public Views of International Involvement from 1964 to 1993: Time-Series Analyses of General and Militant Internationalism.” Journal of Conflict Resolution 43 (1): 23–44.

Chapman, Terrance L. 2011. Securing Approval: Domestic Politics and Multilateral Authorization for War. Chicago: University of Chicago Press.

Converse, Jean M., and Stanley Presser. 1986. Survey Questions: Handcrafting the Standardized Questionnaire. Quantitative Applications in the Social Sciences. Thousand Oaks, CA: Sage Publications, Inc.

Converse, Philip E. 1964. “The Nature of Belief Systems in Mass Publics.” In Ideology and Discontent, edited by David Apter. New York: Free Press.

Drezner, Daniel W. 2008. “The Realist Tradition in American Public Opinion.” Perspectives on Politics 6 (1): 51–70.

Druckman, James, and Lawrence Jacobs. 2015. Who Governs? Presidents, Public Opinion, and Manipulation. Chicago: The University of Chicago Press.

Edwards III, George C. 2000. “Building Coalitions.” Presidential Studies Quarterly 30 (1): 47–78.

Eichenberg, Richard. 2005. “Victory Has Many Friends: US Public Opinion and the Use of Military Force.” International Security 30 (1): 140–77.

———. 2016. “Gender Differences in American Public Opinion on the Use of Military Force, 1982-2013.” International Studies Quarterly, Research Note, 60 (1): 138–48.

Finnemore, Martha. 1996. “Constructing Norms of Humanitarian Intervention.” In The Culture of National Security, edited by Peter Katzenstein. New York: Columbia University Press.

———. 2003. The Purpose of Intervention. Ithaca, NY: Cornell University Press. Foust, Joshua. 2012. “Syria and the Pernicious Consequences of Our Libya Intervention.” The

Atlantic. February 6. http://www.theatlantic.com/international/archive/2012/02/syria-and-the-pernicious-consequences-of-our-libya-intervention/252631/.

Gartner, Scott Sigmund, and Gary M. Segura. 1998. “War, Casualties, and Public Opinion.” Journal of Conflict Resolution 42 (3): 278–300.

Gelpi, Christopher, Peter Feaver, and Jason Reifler. 2009. Paying the Human Costs of War: American Public Opinion and Casualties in Military Conflicts. Princeton: Princeton University Press.

36

Geys, Benny. 2010. “Wars, Presidents, and Popularity: The Political Cost(s) of War Re-Examined.” Public Opinion Quarterly 74 (2): 357–74.

Groeling, Tim, and Matthew Baum. 2008. “Crossing the Water’s Edge: Elite Rhetoric, Media Coverage, and the Rally-Round-the-Flag Phenomenon.” Journal of Politics 70 (4): 1065–85.

Holsti, Ole R. 1992. “Public Opinion and Foreign Policy: Challenges to the Almond-Lippmann Consensus.” International Studies Quarterly, Mershon Series: Research Programs and Debates, 36 (4): 439–66.

Hurwitz, Jon, and Mark Peffley. 1987. “How Are Foreign Policy Attitudes Structured? A Hierarchical Model.” American Political Science Review 81 (4): 1099–1120.

Jackson, Michael P. 1991. “Draft Comments, Michael Jackson, Presidential Letter to College Students.” Box 80, White House Office of Speechwriting, Speech File Draft File, Chron File, 1989-1993, folder “Letters to College Students, 1/7/1991” OA/ID: 13553-003. George H.W. Bush Presidential Library.

Jacobs, Lawrence, and Robert Shapiro. 2000. Politicians Don’t Pander: Political Manipulation and the Loss of Democratic Responsiveness. Chicago: University of Chicago Press.

Jentleson, Bruce. 1992. “The Pretty Prudent Public: Post Post-Vietnam American Opinion on the Use of Military Force.” International Studies Quarterly 36 (1): 49–73.

Jentleson, Bruce, and Rebecca L. Britton. 1998. “Still Pretty Prudent: Post-Cold War American Public Opinion on the Use of Military Force.” Journal of Conflict Resolution 42 (4): 395–417.

Kam, Cindy D., and Jennifer M. Ramos. 2008. “Joining and Leaving the Rally: Understanding the Surge and Decline in Presidential Approval Following 9/11.” Public Opinion Quarterly 72 (4): 619–50.

Kernell, Samuel. 1997. Going Public: New Strategies of Presidential Leadership. 3rd ed. Washington, DC: Congressional Quarterly Inc.

Kertzer, Joshua D. 2013. “Making Sense of Isolationism: Foreign Policy Mood as a Multilevel Phenomenon.” Journal of Politics 75 (1): 225–40.

Kertzer, Joshua D., and Kathleen M. McGraw. 2012. “Folk Realism: Testing the Microfoundations of Realism in Ordinary Citizens.” International Studies Quarterly 56 (2): 245–58.

Kertzer, Joshua D., Kathleen E. Powers, Brian C. Rathbun, and Ravi Iyer. 2014. “Moral Support: How Moral Values Shape Foreign Policy Attitudes.” Journal of Politics 76 (3): 825–40.

Koh, Harold Hongju. 2016. “Address: The War Powers and Humanitarian Intervention.” Houston Law Review 53 (4): 971–1033.

Krebs, Ronald R. 2015. Narrative and the Making of US National Security. Cambridge: Cambridge University Press.

Krebs, Ronald R., and Patrick Thaddeus Jackson. 2007. “Twisting Tongues and Twisting Arms: The Power of Political Rhetoric.” European Journal of International Relations 13 (1): 35–66.

Kreps, Sarah. 2010. “Elite Consensus as a Determinant of Alliance Cohesion: Why Public Opinion Hardly Matters for NATO-Led Operations in Afghanistan.” Foreign Policy Analysis 6 (3): 191–215.

———. 2011. Coalitions of Convenience: United States Military Interventions After the Cold War. New York: Oxford University Press.

37

Kreps, Sarah, and Sarah Maxey. 2017. “Mechanisms of Morality: Sources of Support for Humanitarian Interventions.” Journal of Conflict Resolution Forthcoming: 1–29. doi:10.1177/0022002717704890.

Kull, Steven, Clay Ramsay, and Evan Lewis. 2003. “Misperceptions, the Media, and the Iraq War.” Political Science Quarterly 118 (4): 569–98.

Larson, Eric V. 1996. Casualties and Consensus: The Historical Role of Casualties in Domestic Support for U.S. Military Operations. Santa Monica, CA: Rand.

Lipset, Seymour Martin. 1988. “American Exceptionalism Reaffirmed.” International Review of Sociology 2 (3): 25–69.

Lowe, Will. 2015. Yoshikoder: Cross-Platform Multilingual Content Analysis (version 0.6.5). Java Software Version 0.6.5.

Mandelbaum, Michael, and William Schneider. 1979. “The New Internationalisms: Public Opinion and American Foreign Policy.” In Eagle Entangled: U.S. Foreign Policy in a Complex World, edited by Kenneth A. Oye, Donald Rothchild, and Robert J. Lieber, 34–90. New York: Longman, Inc.

McDermott, Rose. 2011. “Internal and External Validity.” In Cambridge Handbook of Experimental Political Science, edited by James Druckman, Donald Green, James Kuklinski, and Arthur Lupia. New York: Cambridge University Press.

Morgenthau, Hans J. 1951. In Defense of the National Interest. New York: Alfred A. Knopf. Mutz, Diana C., and Robin Pemantle. 2015. “Standards for Experimental Research: Encouraging

a Better Understanding of Experimental Methods.” Journal of Experimental Political Science 2 (2): 192–215.

Obama, Barack. 2013. “Remarks by the President in Address to the Nation on Syria.” Office of the Press Secretary. September 10. https://www.whitehouse.gov/the-press-office/2013/09/10/remarks-president-address-nation-syria.

———. 2014. “Statement by the President on ISIL.” Whitehouse.gov. September 10. https://www.whitehouse.gov/the-press-office/2014/09/10/statement-president-isil-1.

Oppenheimer, Daniel M., Tom Meyvis, and Nicolas Davidnko. 2009. “Instructional Manipulation Checks: Detecting Satisficing to Increase Statistical Power.” Journal of Experimental Social Psychology 45 (4): 867–72.

Pew Research Center, U.S. Politics and Policy, 1615 L. 2014. “Bipartisan Support for Obama’s Military Campaign Against ISIS.” Pew Research Center for the People and the Press. September 15. http://www.people-press.org/2014/09/15/bipartisan-support-for-obamas-military-campaign-against-isis/.

Reiter, Dan, and Allan Stam. 2002. Democracies at War. Princeton: Princeton University Press. Saunders, Elizabeth N. 2011. Leaders at War: How Presidents Shape Military Interventions.

Ithaca, NY: Cornell University Press. Schneider, William. 1983. “Conservatism, Not Interventionism: Trends in Foreign Policy

Opinion, 1974-1982.” In Eagle Defiant: United States Foreign Policy in the 1980s, 33–64. Boston: Little, Brown and Company.

Schultz, Kenneth. 2003. “Tying Hands and Washing Hands: The U.S. Congress and Multilateral Humanitarian Intervention.” In Locating the Proper Authorities: The Interaction of International and Domestic Institutions, edited by Daniel W. Drezner. Ann Arbor: University of Michigan Press.

Tomz, Michael. 2007. “Domestic Audience Costs in International Relations: An Experimental Approach.” International Organization 61 (4): 821–40.

38

Tomz, Michael, and Jessica Weeks. 2013. “Public Opinion and the Democratic Peace.” American Political Science Review 107 (4): 849–65.

Trager, Robert F., and Lynn Vavreck. 2011. “The Political Costs of Crisis Bargaining: Presidential Rhetoric and the Role of Party.” American Journal of Political Science 55 (3): 526–45.

Western, Jon. 2005. Selling Intervention and War: The Presidency, the Media, and the American Public. Baltimore: The Johns Hopkins University Press.

Wheeler, Nicholas. 2000. Saving Strangers: Humanitarian Intervention in International Society. Oxford: Oxford University Press.

———. 2004. “The Humanitarian Responsibilities of Sovereignty: Explaining the Development of a New Norm of Military Intervention for Humanitarian Purposes in International Society.” In Humanitarian Intervention and International Relations, edited by Jennifer Welsh, 29–51. New York: Oxford University Press.

Wittkopf, Eugene R. 1986. “On the Foreign Policy Beliefs of the American People: A Critique and Some Evidence.” International Studies Quarterly 30 (4): 425–45.

———. 1987. “Elites and Masses: Another Look at Attitudes toward America’s World Role.” International Studies Quarterly 31 (2): 131–59.

———. 1990. Face of Internationalism: Public Opinion and American Foreign Policy. Durham, NC: Duke University Press.

———. 1994. “Faces of Internationalism in a Transitional Environment.” Journal of Conflict Resolution 38 (3): 376–401.

Wittkopf, Eugene R., and Michael A. Maggiotto. 1983. “The Two Faces of Internationalism: Public Attitudes Toward American Foreign Policy in the 1970s--And Beyond?” Social Science Quarterly 64 (2): 288–304.

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APPENDICES Appendix A. Examples of Humanitarian Justifications Appendix B. Measuring Justifications for Intervention 1. Description of Content Analysis 2. Dictionary of Humanitarian Justifications 3. Dictionary of Security Justifications 4. Constructing a Dataset of Justifications for Potential Interventions

5. Analysis of Justification Pattern for All Potential U.S. Military Interventions, 1990-2013 6. Analysis of Security Justifications

Appendix C. “Very Important” Foreign Policy Goals 1. Foreign Policy Goals Associated with Cooperative and Militant Internationalism 2. Importance of Cooperative Internationalist Goals 3. Importance of Militant Internationalist Goals Appendix D. Experiment One 1. Survey Instrument 2. Experiment One Sample Demographics 3. Results of Manipulation Check 4. Analysis Including Respondents Who Failed the Manipulation Check 5. All Measures of Political Engagement by Foreign Policy Beliefs Appendix E. Experiment Two 1. Survey Instrument 2. Experiment Two Sample Demographics

3. Replication of Main Results from Experiment One 4. Results of Manipulation Check 5. Analysis Including Respondents Who Failed Manipulation Check 6. The Political Costs of Adding Humanitarian Justifications

Appendix F. Stability of Responses Over Time Appendix G. Testing the Effects of Expert Agreement 1. Expert Agreement Follow-Up Survey Instrument 2. Effect of Expert Agreement on Support: Results and Analysis Appendix References

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APPENDIX A. EXAMPLES OF HUMANITARIAN JUSTIFICATIONS A1. Examples of Humanitarian Justifications in All Post-Cold War Interventions

Case Principle

Policy Objective

Example of Humanitarian Justification

Gulf War (1991) Security

“Iraq’s brutality against innocent civilians will not be permitted to stand. And Saddam Hussein’s violations of international law will not stand. His aggression against Kuwait will not stand” (G. H. W. Bush 1990).

Somalia (1992-93) Humanitarian

“I have to remind my fellow Americans and all of the people in the world who have an aversion to the events of the last two weeks not to forget that over 300,000 people lost their lives there, were starved, were murdered, were subject to incredibly inhumane conditions because of the chaotic and lawless behavior of the people who had authority” (Clinton 1993).

Haiti (1994) Security “Our reasons are clear: to stop the horrific atrocities that threaten

thousands of men, women, and children in Haiti” (Clinton 1994b).

Bosnia (1994-95) Humanitarian

“Two weeks ago, in a murderous attack, a single shell killed 68 people in the city’s market. And last week with our NATO allies, we said that those who would continue terrorizing Sarajevo must pay a price” (Clinton 1994a).

Kosovo (1999) Humanitarian

“I think the most important thing now is for us to save lives, return people to their homes, get them the humanitarian aid they need, and to remove completely and irrevocably the threat of aggression by the Serb military and other forces in Kosovo” (Clinton 1998).

Afghanistan (2001-14) Security

“Not only is our military destroying those who would harbor evil…but we’re liberators. We’re freeing women and children from incredible oppression” (G. W. Bush 2002).

Iraq (2003-10) Security

“We care about those who suffer under the hands of dictator in Iraq. We care deeply about those who dissent and then are tortured, about those who express an opinion other than what the dictator thinks and are raped and mutilated. The condition of the Iraqi citizen is on our mind and in our heart” (G. W. Bush 2003).

Libya (2011) Humanitarian “The United States of America is different. And as president, I refused to wait for the images of slaughter and mass graves before taking action” (Obama 2011).

Syria/ISIL (2014) Security

“When we helped prevent the massacre of civilians trapped on a distant mountain, here’s what one of them said: ‘We owe our American friends our lives. Our children will always remember that there was someone who felt our struggle and made a long journey to protect innocent people.’ That is the difference we make in the world” (Obama 2014).

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APPENDIX B. MEASURING JUSTIFICATIONS FOR INTERVENTION B1. Description of Content Analysis Collecting National Addresses

Working from a list of potential interventions for the post-Cold War period, I searched the Public Papers of the Presidents database to collect all national addresses that mentioned a target state for the relevant year. Statements considered national addresses were prepared messages given by the President in an official capacity that either: 1) were given from the White House, or 2) explicitly identified the nation as a whole as the immediate audience. These selection criteria exclude the non-prepared portions of news conferences and exchanges with the press—i.e., responses to questions following the president’s opening statement—as well as remarks given on the campaign trail or at events or fundraisers. It also excludes proclamations and memos to Congress that were written rather than spoken communications. Commonly included statements are State of the Union addresses, weekly radio addresses, the prepared portions of news conferences, and statements on events or crises. The resulting sample contains 801 speeches from George H.W. Bush, Bill Clinton, George W. Bush, and Barack Obama covering the 24 years from 1990 to 2013. 602 of these speeches addresses a potential intervention that ended in the use of force. While this sample does not capture every presidential justification for military force, it holds constant the intended audience and factors such as audience partisanship, connections to the military, and location that could influence leaders’ choice of justification. Limiting the sample to prepared remarks also ensures that the justifications used are intentional and reflect a political message the White House planned to communicate. Developing Dictionaries of Justifications

From the national addresses, I then randomly sampled five speeches from each year to read and code justifications for intervention. Based on this manual coding, I inductively developed two categories of justifications: humanitarian and security. The manual coding also revealed that presidents relied on ideological justifications, focused on the protection and promotion of democracy and other U.S. values. These justifications combined concerns with U.S. security—presidents directly link the benefits of democracy promotion to regional stability and the protection of U.S. interests—and foreign civilians—freedom and representative governance are presented as in the interest of citizens in the target state. However, unlike security and humanitarian claims, these justifications alone cannot provide a sufficient rationale for military action, nor do they generate clear theoretical expectations for cooperative and militant internationalists. Additionally, compared to humanitarian and security justifications ideological claims were used in negligible numbers over the post-Cold War period. Thus, the dataset focuses on security and humanitarian justifications and for the purposes of this article I further narrow the focus to the pattern of humanitarian justifications.

I then created lists of words associated with each category of justifications, searched the sample for occurrences of these words, and calculated the rate at which each word correctly corresponded to its justification category. Phrases that consistently and correctly identified the relevant justification were included in the dictionaries for each category. I imported the dictionaries into the Yoshikoder content analysis program (Lowe 2015) to calculate the number

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of times presidents used each category of justifications in national addresses that referenced at least one case of potential intervention. Managing the Risks of Automated Content Analysis

Automated content analysis is invaluable for systematically examining the pattern and consequences of presidents’ justifications for military action because the volume of text in presidential speeches makes comprehensive manual coding infeasible; however, the method requires strong assumptions. Most significantly, content analysis assumes a stable communication process in which words have the same meaning every time they are used (Krebs 2015, 301). The paper follows Krebs’ (2015, 301) suggestions for mitigating concerns about instability by “analyzing a narrower range of texts—from a single or relatively homogeneous set of speakers, from a relatively short time span, from a single country—and by generating search-terms and coding rules based on a context-sensitive reading of select tests and secondary literature.” First, the paper focuses on four presidents of a single country within a 24-year period in which the international system and the U.S.’s position in it remained relatively stable. This focus assuages concerns about major rhetorical shifts or changing points of reference. In other words, these administrations faced similar threats, had access to the same toolkit of justifications, and addressed voting publics with many shared historical experiences. Second, the dictionaries used to measure each justification category were created based on a context-sensitive manual coding of a sample of speeches and their exclusivity to the given justification category.

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B2. Dictionary of Humanitarian Justifications Humanitarian

Phrases Percentage

Correct Humanitarian

Phrases Percentage

Correct abhorrent 100% savage 100% appalled 100% shelling 100% atrocit* 100% siege 100% barbarism 100% slaughter 100% bodies 100% snipers 100% cleansing 100% starvation 100% concentration 100% starving 100% conscripting 100% refuge* 90% convoy 100% population 90% defenseless 100% brutal* 89% detained 100% humanitarian 87% dying 100% displac* 83% egregious 100% civilians 82% exhausted 100% suffering 80% flee 100% surviv* 80% genocid* 100% airdrops 80% heinous 100% suffer 77% huddle 100% tortur* 75% immoral 100% hospitals 71% inhumane 100% ethnic* 71% Kosovars 100% universal 70% malnourished 100% innocent 69% massacre 100% supplies 67% mutilation 100% rations 67% norms 100% delivery 66% oppression 100% horrif* 66% palaces 100% nightmare 66% reconstruction 100% rape 66% revulsion 100%

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B3. Dictionary of Security Justifications Security Phrases

Percentage Correct

Security Phrases

Percentage Correct

arming 100% comply 83% autonomy 100% mass 81% axis 100% invade 80% battalions 100% stability 80% bunker 100% inspect* 76% centrifuge 100% occup* 75% defiance 100% territor* 75% degrade 100% resort 75% destabiliz* 100% chaos 75% disarm* 100% destroy 73% equipping 100% withdraw 73% exercises 100% extremist 73% germ 100% offensive 73% harbor 100% defeat 72% hijacker 100% victory 72% hostility 100% enrichment 71% IEDs 100% biological 70% jets 100% weapons 68% provocation 100% strike 68% scud 100% raids 67% spillover 100% fronts 67% strongholds 100% isolat* 67% uranium 100% neighboring 67% sovereign* 95% ballistic 67% aggression 95% defy 67% killers 88% outlaw 67% destruction 87% aerial 67% missiles 86% dismantle 63% plot 85% surge 63% deter 83% warfare 60% unarmed 83% invasion 60% militia 83%

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B4. Constructing a Dataset of Justifications for Potential Interventions The results presented in the main text highlight the pattern of justifications for all cases of

U.S. military intervention from 1990 to 2013. This data is drawn from a larger, original dataset designed to capture patterns of humanitarian and security justifications for all potential U.S. interventions during this period. While a full description of trends across justification types is beyond the scope of this article, the results presented in B5 below demonstrate that the pattern of humanitarian justifications highlighted in the text holds when all potential interventions are considered.

The dataset of justifications is built on the assumption of democratic accountability—for

a military intervention to take place, the president needs public approval, and before the president can ask the public to support intervention he or she must first make sure they are aware of the underlying crisis. It thus includes cases in which there was an increased likelihood of military hostilities (Wilkenfeld and Brecher 1984) and the crisis warranted sufficient public attention by the president to create the possibility of an official justification for action.

The starting point for the dataset was all cases listed in either the UCDP Armed Conflict (Pettersson and Wallensteen 2015) or the Militarized Interstate Disputes (MID) datasets (Palmer et al. 2015). I consider the crises from these two sources because UCDP provides good coverage of low-level internal conflicts, but omits a number of conflicts that escalated from international threats, while the MID data captures international crises, but omits states’ threats against their own citizens. When taken together, the two sources provide a comprehensive list of intra- and interstate crises for the 1990 to 2013 period. To establish which cases received public presidential attention, I then searched the Public Papers of the Presidents database for references to crises in either the UCDP or the MID. Cases were included in the new dataset of potential interventions if they met each of the following three criteria: 1) the crisis was publically mentioned by the president in an official speech or document; 2) the mention addressed a specific and immediate crisis in detail; and 3) the mention implied that the U.S. was willing to take coercive action to address the crisis.

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B5. Analysis of Justification Pattern for All Potential U.S. Military Interventions, 1990-2013

Use and Emphasis of Humanitarian Justifications in Potential Interventions Humanitarian

Interventions Security

Interventions Humanitarian Justifications

184 (71%)

330 (57%)

Emphasis

52% 29%

Total Speeches 261 579 Note: Emphasis reports average percentage of claims that were humanitarian in speeches addressing each intervention type.

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B6. Analysis of Security Justifications

Use and Emphasis of Security Justifications in Interventions Humanitarian

Interventions Security

Interventions Security Justifications

70 (59%)

349 (72%)

Emphasis

28% 55%

Total Speeches 119 483 Note: Emphasis reports average percentage of claims that referenced security in speeches addressing each intervention type.

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APPENDIX C. “VERY IMPORTANT” FOREIGN POLICY GOALS C1. Foreign Policy Goals Associated with Cooperative and Militant Internationalism These policies are taken from Mandelbaum and Schneider (1979, 41–42). Reponses were collected from 13 waves of the Chicago Council on Global Affairs surveys.

Foreign Policy Beliefs Associated Foreign Policy Goals

Cooperative Internationalism

Keeping peace in the world. Securing adequate supplies of energy. Fostering international cooperation to solve common problems, such as food, inflation, and energy. Worldwide arms control. Helping solve world inflation. Combating world hunger. Maintaining a balance of power. Strengthening the United Nations. Helping to improve the standard of living in less developed countries.

Militant Internationalism

Containing Communism Protecting the interests of American business abroad. Strengthening countries who are friendly toward us. Defending our allies’ security. Protecting weaker nations against foreign aggression. Helping to bring a democratic form of government to other nations. Promoting the development of capitalism abroad.

C2. Importance of Cooperative Internationalist Goals 1974 1979 1982 1987 1995 1998 2001 2002 2008 2010 2012 2014 2015 Keeping peace in the world.

85 -- -- -- -- -- -- -- -- -- -- -- --

Securing adequate supplies of energy.

76 78 70 69 62 64 69 75 80 68 -- 66 61

Fostering international cooperation to solve common problems, such as food, inflation, and energy.

66 -- -- -- -- -- -- -- -- -- -- -- --

Worldwide arms control.

66 64 64 69 -- -- -- -- -- -- -- -- --

Helping solve world inflation.

64 -- -- -- -- -- -- -- -- -- -- -- --

Combating world hunger

60 59 58 63 56 62 34 61 46 42 42 42 42

Maintaining a balance of power.

48 -- -- -- -- -- -- -- -- -- -- -- --

Strengthening the United Nations.

46 47 48 46 51 45 46 57 39 37 35 37 --

Helping to improve the standard of living in less developed countries.

39 35 35 37 22 29 20 30 -- -- -- -- --

Average 61 57 55 57 48 50 43 56 55 49 37 48 52

C3. Importance of Militant Internationalist Goals 1974 1979 1982 1987 1995 1998 2001 2002 2008 2010 2012 2014 2015 Containing Communism.

55 60 59 57 -- -- -- -- -- -- -- -- --

Protecting the interests of American business abroad.

39 45 44 43 52 -- 30 49 -- -- -- 44 --

Strengthening countries who are friendly toward us.

38 -- -- -- -- -- -- -- -- -- -- -- --

Defending our allies’ security.

33 50 50 56 41 44 -- 57 -- -- -- 38 38

Protecting weaker nations against foreign aggression.

28 34 -- 32 24 32 -- 41 24 24 -- 25 --

Helping to bring a democratic form of government to other nations.

28 26 29 30 25 29 24 34 17 -- 14 17 --

Promoting the development of capitalism abroad.

17 -- -- -- -- -- -- -- -- 19 -- -- --

Average 34 43 46 44 36 35 27 45 21 22 14 31 38

APPENDIX D: EXPERIMENT ONE D1. Survey Instrument The experimental data analyzed in this article was collected as part of a larger study that included multiple experiments, some of which were designed for other purposes. However, the respondents analyzed here did not receive any other treatments and the questions relevant to this study were asked first. Appendix D1 presents all treatments and questions that were relevant to this analysis and referenced in the article’s text. Foreign Policy Beliefs and Demographics First, we are going to ask you a few background questions. What is your gender?

• Female • Male • Other

Which of the following best reflects the role you think the United States should play in the world: (response options randomized)

• It is essential for the United States to work with other nations to solve problems such as overpopulation, hunger, and pollution.

• It is important for the United States to maintain a strong military to ensure world peace. • It is best for the future of the United States if we stay out of world affairs.

What is the last grade or class that you completed in school?

• None or grades 1-8 • High school incomplete (grades 9-11) • High school graduate (grade 12 or GED certificate) • Technical, trade, or vocational school after high school • Some college, no 4-year degree (including 2 year Associates Degree) • College graduate (BS, BA, or other 4-year degree) • Post-graduate training or professional schooling after college

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Treatment Conditions Now you are going to read about a situation the U.S. has faced many times in the past and will likely face again in the future. The situation reflects actions taken by presidents from both political parties. It is NOT about the current president and it is NOT about any specific country in the news today. "My fellow Americans, tonight I want to talk to you about the situation in Numar--why it matters, and where we go from here. The regime in Numar poses a grave threat to [its own civilians, including innocent women and children/the security of the United States, including the American people/its own civilians and the security of the United States]. It has [killed thousands of its own people and directly targeted civilians/invaded its neighboring state and threatened the United States/invaded its neighboring state and killed thousands of its own people]." "This is not a world we should accept. The safety of [Numar's civilians/the United States/Numar’s civilians and the United States] is at stake and we must act. This is why, after careful deliberation, I have determined that the United States must respond to this crisis with military action." After the President’s address, most experts publicly agreed with the President’s reasons for intervention. They, too thought the U.S. action would [protect Numar’s civilians/protect U.S. security/protect Numar’s civilians and U.S. security]. Summary:

• The U.S. President has announced his plans to take military action in Numar. • He said the U.S. must act to protect [Numar’s civilians/U.S. security/Numar’s civilians

and U.S. security]. • Experts publicly agreed with the President’s reasons for intervention. • Experts said military action would mainly protect [Numar’s civilians/U.S.

security/Numar’s civilians and U.S. security].

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Follow-Up Questions Would you oppose or favor U.S. military action in this situation?

• Oppose strongly • Oppose somewhat • Favor somewhat • Favor strongly

Which of the following actions would you be willing to take to show your support or opposition to this military action? Check all that apply. (Response order randomized)

• Use social media to express my opinion about the military action. • Sign a petition about the military action. • Write a letter to the editor of a newspaper expressing my opinion about the military

action. • Contact my Member of Congress to express my opinion about the military action. • Participate in a rally about the military action. • None of the above.

Additional Demographics In general, do you think of yourself as:

• Extremely liberal • Liberal • Slightly liberal • Moderate, middle of the road • Slightly conservative • Conservative • Extremely conservative

Generally speaking, when it comes to political parties in the U.S., how would you describe yourself?

• Strong Democrat • Democrat • Independent close to Democrat • Independent (close to neither) • Independent close to Republican • Republican • Strong Republican

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Did you vote in the 2016 general election? • No. • I usually vote, but did not in 2016. • I am not sure. • Yes. I definitely voted.

Manipulation Check To the best of your recollection, in the previous section, what reasons did the hypothetical president give for taking military action in Numar? (response order randomized)

• Only humanitarian goals. The president talked about protecting the civilians of Numar. • Only security goals. The president talked about the safety of the United States. • Both humanitarian and security goals. The president talked about protecting the civilians

of Numar and the safety of the United States. • Neither humanitarian nor security goals. The president didn’t mention protecting the

civilians of Numar or the safety of the U.S.

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D2. Experiment One Sample Demographics The survey was conducted using Survey Sampling International (SSI) from July 14, 2017 to July 28, 2017. The sample included 834 U.S. adults, 497 of whom passed the manipulation check and are included in the analysis. SSI uses an opt-in method to recruit participants and then randomizes invitations to participate in the survey. The result is a nationally diverse sample of registered voters (Kertzer and Zeitzoff 2017, 5). In addition to SSI’s standard population targeting, this sample also targeted Census levels on education and gender.

Variable Number of Respondents

Percentage of Respondents

Party ID24 Democrat 404 49%

Independent 177 21% Republican 252 30%

Ideology Liberal 303 36%

Moderate 300 36% Conservative 231 28%

Education25

High School 185 22% College 547 66%

Post-Graduate 98 12% Gender

Male 424 51% Female 409 49% Other 1 <1%

Foreign Policy Belief

Cooperative Internationalist 420 50% Militant Internationalist 288 35%

Isolationist 126 15% N=834

24 Independents are coded as respondents who identified as independent and close to neither Democrat nor Republican. Respondents who leaned Democrat or Republican were included in the respective party. 25 Based on the highest level of education the respondent entered.

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D3. Results of Manipulation Check Compared to the MTurk sample presented below, a much lower percentage of individuals in the SSI sample passed the manipulation check. The most common mistake for individuals in the humanitarian and security conditions was to assume the president had used both justifications. Without limiting the analysis to individuals who passed the manipulation check, the sample would thus include a sizeable number of respondents whose decisions to support or oppose intervention were driven by justifications other than those presented in the treatment condition.

Recollection of President’s Justifications by Treatment To the best of your recollection, in the previous section, what reasons did the hypothetical president give for taking military action in Numar?

Humanitarian Treatment

Security Treatment

Combined Treatment

Humanitarian 49 % 7 % 16 % Security 9 % 59 % 10 % Combined 40 % 28 % 71 % None of the Above 3 % 6 % 3 % N 278 276 280

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D4. Analysis Including Respondents Who Failed the Manipulation Check D4.1 Measures of Political Engagement by Foreign Policy Beliefs (All Respondents) Index Score Voted in 2016 Cooperative Internationalists 1.36

(0.06)

0.76 (0.02)

Militant Internationalists 1.16*

(0.07)

0.74 (0.03)

Isolationists 1.18 (0.11)

0.58* (0.04)

N 834 833 Table reports the results of two-tailed comparison of means tests (index score) and tests of proportions (voted in 2016) that compared each category of foreign policy beliefs to the cooperative internationalist baseline. Standard errors reported in parentheses. *p<0.05.

D4.2 Support for Humanitarian Justifications by Foreign Policy Beliefs (All Respondents) Humanitarian Difference from

Cooperative Internationalists Cooperative Internationalists

0.64 (0.04)

Militant Internationalists

0.66 (0.05)

0.02 (0.07)

Isolationists 0.30 (0.06)

0.34* (0.07)

N 278 Table reports results from two-tailed tests of proportions. Standard errors reported in parentheses. *p<0.05.

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D4.3 Support for Security and Combined Justifications by Foreign Policy Belief (All Respondents) Security Combined Difference Cooperative Internationalists

0.55 (0.04)

0.64 (0.04)

0.08 (0.06)

Militant Internationalists

0.81 (0.04)

0.77 (0.04)

0.05 (0.06)

Isolationists 0.58 (0.09)

0.38 (0.08)

0.20 (0.12)

N 276 280 Table reports results from two-tailed tests of proportions. Standard errors reported in parentheses. *p<0.05.

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D5. All Measures of Political Engagement by Foreign Policy Beliefs Cooperative

Internationalists Militant

Internationalists Isolationists

Index Score 1.43 (0.08)

1.10* (0.08)

1.27 (0.16)

Social Media 0.41 (0.03)

0.34 (0.03)

0.31 (0.06)

Petition 0.46 (0.03)

0.36* (0.04)

0.37 (0.06)

Letter to the Editor 0.10 (0.02)

0.09 (0.02)

0.16 (0.05)

Contact Member of Congress

0.32 (0.03)

0.26 (0.03)

0.34 (0.06)

Rally 0.14 (0.02)

0.05* (0.02)

0.07 (0.03)

None of the Above 0.28 (0.03)

0.31 (0.04)

0.33 (0.06)

Voted in 2016 0.77 (0.02)

0.72 (0.04)

0.60* (0.06)

N 267 163 67 Table reports the results of two-tailed comparison of means tests (index score) and tests of proportions (all other variables) that compared each category of foreign policy beliefs to the cooperative internationalist baseline. Sample is limited to individuals who passed the manipulation check. Standard errors reported in parentheses. *p<0.05.

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APPENDIX E. EXPERIMENT TWO E1. Survey Instrument As before, this experimental data was collected as part of a larger study that included multiple questions and experiments, some of which were designed for other purposes. However, the respondents analyzed here did not receive any other treatments and the questions relevant to this study were asked first. Appendix E1 presents all treatments and questions that were relevant to this analysis and referenced in the article’s text. Foreign Policy Beliefs and Demographics First, we are going to ask you a few background questions. What is your gender?

• Female • Male • Other

Which of the following best reflects the role you think the United States should play in the world: (response options randomized)

• It is essential for the United States to work with other nations to solve problems such as overpopulation, hunger, and pollution.

• It is important for the United States to maintain a strong military to ensure world peace. • It is best for the future of the United States if we stay out of world affairs.

Did you vote in the 2012 general election?

• No. • I usually vote, but did not in 2012. • I am not sure. • Yes. I definitely voted.

What is the last grade or class that you completed in school?

• None or grades 1-8 • High school incomplete (grades 9-11) • High school graduate (grade 12 or GED certificate) • Technical, trade, or vocational school after high school • Some college, no 4-year degree (including 2 year Associates Degree) • College graduate (BS, BA, or other 4-year degree) • Post-graduate training or professional schooling after college

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Treatment Conditions Now you are going to read about a situation the U.S. has faced many times in the past and will likely face again in the future. The situation reflects actions taken by presidents from both political parties and is NOT about any specific country in the news today. Over the last few months, a violent conflict has developed in the country of Numar. In his address to the nation about this conflict, the U.S. president said: “My fellow Americans, tonight I want to talk to you about the situation in Numar—why it matters, and where we go from here. The regime in Numar poses a grave threat to [its own civilians, including innocent women and children/the security of the United States, including the American people/its own civilians and the security of the United States]. It has [killed thousands of its own people and directly targeted civilians/created a safe haven for terrorists and threatened the United States/created a safe haven for terrorists and killed thousands of its own people].” “This is not a world we should accept. The safety of [Numar’s civilians/the United States/Numar’s civilians and the United States] is at stake and we must act. This is why, after careful deliberation, I have determined that the United States must respond to this crisis with military action.” After the President’s address, most experts publicly [agreed with/disputed] the President’s reasons for intervention. [They, too/they] thought [1-7 from table below].

Experts thought… Humanitarian Security Combo

Sincere

(1)…the U.S. action would protect Numar’s civilians.

(2)…the U.S. action would protect U.S. security.

(3)…the U.S. action would protect Numar’s civilians and U.S. security.

Insincere

(4)… instead of concern for civilians, the real motivation of the U.S. action was to protect U.S. security.

(5)… instead of concern for U.S. security the real motivation of the U.S. action was to protect Numar’s civilians.

(6)… instead of concern for civilians the only motivation of the U.S. action was to protect U.S. security.

(7)... instead of concern for U.S. security the only motivation of the U.S. action was to protect Numar’s civilians.

Summary:

• The U.S. President has announced his plans to take military action in Numar. • He said the U.S. must act to protect [Numar’s civilians/U.S. security/Numar’s civilians

and U.S. security]. • Experts publicly [agreed with/disputed] the President’s reasons for intervention. • Experts said military action would mainly protect [Numar’s civilians/U.S.

security/Numar’s civilians and U.S. security].

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Follow-Up Questions Support and Opposition Would you oppose or favor U.S. military action in this situation?

• Oppose strongly • Oppose somewhat • Neither oppose nor favor • Favor somewhat • Favor strongly

[Asked only of respondents who select: “Neither oppose nor favor.”] If you had to choose, would you lean towards opposing or favoring military action in this situation?

• Lean towards opposing • Lean towards favoring

Which of the following actions would you be willing to take to show your support or opposition to this military action? Check all that apply. (Response order randomized)

• Use social media to express my opinion about the military action. • Sign a petition about the military action. • Write a letter to the editor of my local newspaper expressing my opinion about the

military action. • Contact my Member of Congress to express my opinion about the military action. • Participate in a protest about the military action. • None of the above.

Intervention Outcomes If the United States takes military action in this case, how likely do you think each of the following outcomes will be: (question order randomized) Civilians in Numar will be safe

• Very unlikely • Somewhat unlikely • Somewhat likely • Very likely

The United States will be more secure.

• Very unlikely • Somewhat unlikely • Somewhat likely • Very likely

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Manipulation Check Just a few more questions about the situation in Numar. To the best of your recollection, what points did the President use to explain the military action in Numar?

• Only humanitarian: the quotes talked about protecting the civilians of Numar. • Only security: the quotes talked about the safety of the United States. • Both humanitarian and security: the quotes talked about protecting the civilians of Numar

and the safety of the United States. • Neither humanitarian nor security: the quotes didn’t mention protecting the civilians of

Numar or the safety of the U.S. Additional Demographics In general, do you think of yourself as:

• Extremely liberal • Liberal • Slightly liberal • Moderate, middle of the road • Slightly conservative • Conservative • Extremely conservative

Generally speaking, when it comes to political parties in the U.S., how would you describe yourself?

• Strong Democrat • Democrat • Independent close to Democrat • Independent (close to neither) • Independent close to Republican • Republican • Strong Republican

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E2. Experiment Two Sample Demographics The survey was conducted using Amazon’s Mechanical Turk from July 14, 2016 to July 23, 2016. The sample included 1,055 U.S. adults, 792 of whom passed the manipulation check. In line with studies of online survey platforms (Berinsky, Huber, and Lenz 2012), respondents were both more liberal, educated, and female than the general population. For the purposes of this study, these biases are expected to inflate the proportion of individuals with cooperative internationalist values and provide the statistical power necessary to conduct the subgroup analysis focused on this group.

Variable Number of Respondents

Percentage of Respondents

Party ID26 Democrat 538 51%

Independent 188 18% Republican 326 31%

Ideology

Liberal 516 49% Moderate 217 21%

Conservative 320 30% Education27

High School 123 12% College 733 69%

Post-Graduate 199 19% Gender

Male 477 45% Female 573 54% Other 4 <1%

Foreign Policy Belief

Cooperative Internationalist 604 57% Militant Internationalist 278 26%

Isolationist 172 16% N=1,055

26 Independents are coded as respondents who identified as independent and close to neither Democrat nor Republican. Respondents who leaned Democrat or Republican were included in the respective party. 27 Based on the highest level of education the respondent entered.

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E3. Replication of Main Results from Experiment One

Humanitarian Security Combined

Difference between

Security and Combined

Cooperative Internationalists

0.71 (0.06)

0.49 (0.06)

0.66 (0.06)

0.17* (0.08)

Militant Internationalists

0.77 (0.08)

0.96 (0.04)

0.91 (0.05)

0.05 (0.06)

Isolationists 0.14 (0.09)

0.37 (0.11)

0.35 (0.11)

0.02 (0.15)

N 110 114 121 Table reports results from two-tailed tests of proportions. Sample is limited to individuals who passed the manipulation check. Standard errors reported in parentheses. *p<0.05.

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E4. Results of Manipulation Check In each treatment condition, the majority of respondents correctly identified the points the president used to explain military action. The most common mistake for individuals in the humanitarian and security conditions was to assumed the president had used both justifications. Incorrect respondents in the combined condition mistakenly remembered the humanitarian versus the security justification in roughly equal numbers.

Recollection of President’s Justifications by Treatment To the best of your recollection, what points did this president use to explain the reasons for military action?

Humanitarian Treatments

Security Treatments

Combined Treatments

Humanitarian 71 % 4 % 11 % Security 6 % 72 % 8 % Combined 20 % 21 % 80 % None of the Above 3 % 3 % 1 % N 303 298 453

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E5. Analysis Including Respondents Who Failed the Manipulation Check Effect of Sincerity by Foreign Policy Belief and Justification Type (All Respondents) Cooperative

Internationalists Militant

Internationalists Isolationists

Humanitarian Sincere 0.61

(0.05) 0.78

(0.06)

0.21 (0.08)

Insincere 0.27 (0.05)

0.73 (0.07)

0.11 (0.06)

Difference 0.34* (0.07)

0.05 (0.09)

0.10 (0.10)

Security Sincere 0.48

(0.05) 0.82

(0.06)

0.33 (0.10)

Insincere 0.40 (0.05)

0.59 (0.07)

0.07 (0.06)

Difference 0.08 (0.07)

0.23* (0.10)

0.27 (0.12)

Combined Sincere 0.60

(0.05) 0.83

(0.06)

0.31 (0.09)

Insincere Humanitarian

0.53 (0.05)

0.86 (0.06)

0.25 (0.08)

Difference 1 0.07 (0.07)

0.02 (0.08)

0.06 (0.12)

Insincere Security

0.52 (0.05)

0.67 (0.08)

0.30 (0.09)

Difference 2 0.08 (0.07)

0.17 (0.10)

0.01 (0.13)

N 604 278 172 Table reports results from two-tailed tests of proportions. Standard errors reported in parentheses. For combined categories, difference 1 reports difference between sincere and insincere humanitarian, difference 2 between sincere and insincere security. *p<0.05.

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E6. The Political Costs of Adding Humanitarian Justifications

One alternative explanation for the prominence of humanitarian justifications in security interventions is that these appeals make for good oratory and are costless additions to presidents’ explanations for military action. To investigate whether humanitarian justifications changed how respondents thought about the intervention—and thus the objectives for which they would hold the president accountable—experiment two included follow-up questions to gauge respondents’ expectations for intervention outcomes. Respondents were asked, “If the U.S. takes military action in this case, how likely do you think each of the following outcomes will be: 1) Civilians in Numar will be safe. 2) The U.S. will be more secure.” The results indicate that the content of the president’s justifications significantly influenced respondents’ expected outcomes.

As the table below shows, a significantly higher proportion of participants in the combined condition expected that civilians would be safe than respondents who read only security justifications. A significantly lower proportion of individuals in the humanitarian condition also expected the U.S. would be more secure compared to individuals in the security condition. These findings suggest that presidents’ justifications are not empty rhetoric. Instead, how the president talks about the necessity of military action shapes public expectations about the intervention’s outcome. Adding humanitarian justifications to security claims thus raises the bar for success and is a politically costly decision. Absent their utility for persuading cooperative internationalists, unnecessarily increasing the stakes of a security intervention by including humanitarian justifications appears risky and ill-advised.

Expected Intervention Outcomes by Treatment Condition Security Humanitarian Combined Civilians in Numar will be safe.

0.30 (0.04)

0.65* (0.05)

0.61* (0.04)

The U.S. will be more secure.

0.66

(0.04)

0.42* (0.05)

0.62

(0.04) N 114 110 121 Table reports results of two-tailed tests of proportions that compare each category of justification to the security baseline. Sample is limited to individuals who passed the manipulation check. Standard errors reported in parentheses. *p<0.05.

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APPENDIX F. STABILITY OF RESPONSES OVER TIME

While the pattern of support is consistently in the direction expected by the domestic

coalition argument, changes in statistical significance based on whether the analysis includes individuals who failed the manipulation check may raise concerns about the robustness and stability of the results. Given concerns about replicability, the results presented in the main analysis were collected as part of a series of nine pretests and follow-up experiments conducted with multiple samples, across different platforms, with alternative security scenarios. These surveys were fielded from May 2016 to May 2017 and help evaluate the influence of key political moments related to the 2016 presidential campaign, as well as subsequent changes in the U.S. political climate.

The above figure illustrates changes in support over time for different categories of justifications disaggregated by respondents’ foreign policy beliefs. While some variability across samples and time is expected, the results show that within each group of foreign policy beliefs responses to justifications are surprisingly stable given the volatility of the political climate during the 2016 presidential campaign.

Of the nine experiments, six produced results that clearly support the domestic coalition argument. The exceptions were the surveys conducted in October 2016, November 2016, and in the second half of December 2016. In the first two cases, proximity to the presidential election appears to correspond with an increase in support for terrorism justifications, which muted the

020

4060

8010

0

05 06 07 08 10 12 05/17Month of Survey

CI MIISO

Humanitarian Justifications

020

4060

8010

005 06 07 08 10 12 05/17

Month of Survey

CI MIISO

Terrorism Justifications

020

4060

8010

0

06 12 12 05/17Month of Survey

CI MIISO

FPR Justifications

020

4060

8010

0

05 07 08 10 12 05/17Month of Survey

CI MI ISO

Combined Humanitarian/Terror

020

4060

8010

0

06 12 12 05/17Month of Survey

CI MIISO

Combined Humanitarian/FPR

Note: Surveys were conducted during 2016 unless otherwise noted.

Figure 8.1 Changes in Support for Justifications Over Time

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effect of adding humanitarian claims. However, responses to terror justifications appeared to return to their previous levels in the May 2017 follow-up. It is worth noting that the weeks immediately preceding and following presidential elections are shown to be periods in which conflict initiation is least likely (Gaubatz 1999).

Differences in the second December 2016 sample warrant a closer look because, alongside the results of experiment one presented in the main text, this was the only other survey conducted with a national sample through SSI. In this case, support for humanitarian and combined justifications remained consistent within subgroups, but cooperative internationalists and isolationists offered higher than normal support for the foreign policy restraint scenario. The most pessimistic interpretation of these results is that the effect of humanitarian justifications on cooperative internationalists is a symptom of the demographics of MTurk samples. However, this interpretation is undermined by: 1) the results of experiment one in the main text which are in line with the overall patterns of support and, 2) the fact that limiting the December SSI sample to respondents who most closely resemble MTurkers does not recover levels of support comparable to the MTurk results.28

Instead, the more likely explanation for these disparate results is a combination of multiple factors. First, the December SSI sample did not include a manipulation check. Comparing the results of manipulation checks for experiment one and experiment two (appendix D3 and E4, respectively) reveal that in comparable surveys, SSI respondents failed the manipulation check in higher percentages than MTurk respondents—41 percent of SSI respondents incorrectly believed the president used humanitarian claims in the security condition compared to only 28 percent of MTurk respondents. If this pattern holds, the security condition from the December SSI sample may contain a sizeable number of respondents who answered the follow-up questions as though they read humanitarian justifications for action, resulting in higher support for the related intervention.

Second, this experiment was fielded in the last two weeks of December 2016 during a period of political transition that included initial reports of Russian hacking related to the presidential election and U.S. retaliation, coverage of Trump administration appointments and transition plans, a terrorist attack on a Christmas market in Germany, and the Christmas holiday. Together, this climate of transition and threat could influence participants’ associations with different types of justifications, altering both their thought process with respect to military action and responses to the treatment scenarios. Without additional data, this explanation cannot be directly evaluated, but evidence that support for security justifications returned to its earlier levels by May 2017 suggests any effect of the presidential transition was not permanent.

Finally, with nine repetitions of the experiment across time and platforms the chance of drawing a sample that produces a null result is not negligible. Therefore, while future research 28 Specifically, the SSI sample targeted Census education levels, which are lower than the average education level of MTurk respondents. Tests of proportions demonstrate that education does not make a significant difference in cooperative internationalists’ support for security justifications (p=0.8022)—the condition where responses contradict the domestic coalition expectations. Additionally, replicating the analysis using only individuals with a college degree revealed higher support for security justifications among educated cooperative internationalists—73 percent compared to 71 percent in the full sample. I also ran the analysis using only the subsets of respondents who were Democrats or had entered college. Neither case returned results comparable to the other experimental findings.

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should consider how different aspects of the political and media environment condition the effects of foreign policy beliefs, the bulk of the evidence indicates that the relationship between foreign policy beliefs and support for alternative justifications is robust across time and samples.

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APPENDIX G. TESTING THE EFFECTS OF EXPERT AGREEMENT G1. Expert Agreement Follow-Up Survey Instrument Treatment Condition #1, No Expert Information Over the last few months, a violent conflict has developed in the country of Numar. In his address to the nation about this conflict, the U.S. President said: "My fellow Americans, tonight I want to talk to you about the situation in Numar--why it matters, and where we go from here. The regime in Numar poses a grave threat to the security of the United States, including the American people. It has invaded its neighboring state and threatened the United States." "This is not a world we should accept. The safety of the United States is at stake and we must act. This is why, after careful deliberation, I have determined that the United States must respond to this crisis with military action." Summary:

• The U.S. President has announced his plans to take military action in Numar. • He said the U.S. must act to protect U.S. security.

No Expert Support/Opposition Would you oppose or favor U.S. military action in this situation?

• Oppose strongly • Oppose somewhat • Favor somewhat • Favor strongly

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Treatment Condition #2, Expert Agreement Over the last few months, a violent conflict has developed in the country of Numar. In his address to the nation about this conflict, the U.S. President said: "My fellow Americans, tonight I want to talk to you about the situation in Numar--why it matters, and where we go from here. The regime in Numar poses a grave threat to the security of the United States, including the American people. It has invaded its neighboring state and threatened the United States." "This is not a world we should accept. The safety of the United States is at stake and we must act. This is why, after careful deliberation, I have determined that the United States must respond to this crisis with military action." After the President’s address, most experts publicly agreed with the President’s reasons for intervention. They, too, thought the U.S. action would protect U.S. security. Summary:

• The U.S. President has announced his plans to take military action in Numar. • He said the U.S. must act to protect U.S. security. • Experts publicly agreed with the President’s reasons for intervention. • Experts said military action would mainly protect U.S. security.

Expert Agreement Support/Opposition Would you oppose or favor U.S. military action in this situation?

• Oppose strongly • Oppose somewhat • Favor somewhat • Favor strongly

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G2. Effect of Expert Agreement on Support: Results and Analysis

Support for Intervention by Expert Information

In response to the main experimental results presented in the article, critics may counter that information about expert agreement inflates support in experiment one and makes it difficult to evaluate the negative effects of insincerity relative to the true baseline of support in experiment two. To clarify the effect of expert agreement on support, I conducted a follow-up experiment that varied whether participants received information about how experts responded to the president’s justifications for military action. This survey was fielded to a sample of 227 U.S. adults on July 12, 2017 through Amazon’s Mechanical Turk.

As the figure above shows, there is no evidence that expert agreement alone had a significant effect on respondents’ support for the intervention. When they received only the president’s security justification for action, 52 percent of respondents supported the intervention. Among respondents who received both the president’s security justification for action and information that experts agreed with the president’s account of the conflict, 54 percent supported the intervention. The absence of any significant difference between these two groups increases confidence that the decline in support in experiment two is a reaction to insincere justifications rather than an artifact of a superficially inflated baseline of support in the sincere conditions.

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Appendix References

Berinsky, Adam, Gregory A. Huber, and Gabriel S. Lenz. 2012. “Evaluating Online Labor Markets for Experimental Research: Amazon.com’s Mechanical Turk.” Political Analysis 20 (3): 351–68.

Bush, George H.W. 1990. “The President’s News Conference in Orlando, Florida.” Public Papers of the Presidents.

Bush, George W. 2002. “Remarks in Aurora, Missouri.” Public Papers of the Presidents. ———. 2003. “Remarks on Improving Counterterrorism Intelligence.” Public Papers of the

Presidents. Clinton, William J. 1993. “The President’s News Conference with Prime Minister Ciampi of

Italy.” Public Papers of the Presidents. ———. 1994a. “The President’s Radio Address and an Exchange With Reporters.” Public

Papers of the Presidents. ———. 1994b. “The President’s Radio Address.” Public Papers of the Presidents. ———. 1998. “Remarks on Departure for Silver Spring, Maryland, and an Exchange with

Reporters.” Public Papers of the Presidents. Gaubatz, Kurt Taylor. 1999. Elections and War: The Electoral Incentive in the Democratic

Politics of War and Peace. Stanford: Stanford University Press. Kertzer, Joshua D., and Thomas Zeitzoff. 2017. “A Bottom-Up Theory of Public Opinion about

Foreign Policy.” American Journal of Political Science 0 (0): 1–16. doi:10.1111/ajps.12314.

Krebs, Ronald R. 2015. Narrative and the Making of US National Security. Cambridge: Cambridge University Press.

Lowe, Will. 2015. Yoshikoder: Cross-Platform Multilingual Content Analysis (version 0.6.5). Java Software Version 0.6.5.

Mandelbaum, Michael, and William Schneider. 1979. “The New Internationalisms: Public Opinion and American Foreign Policy.” In Eagle Entangled: U.S. Foreign Policy in a Complex World, edited by Kenneth A. Oye, Donald Rothchild, and Robert J. Lieber, 34–90. New York: Longman, Inc.

Obama, Barack. 2011. “Address to the Nation on the Situation in Libya.” Public Papers of the Presidents.

———. 2014. “Statement by the President on ISIL.” Whitehouse.gov. September 10. https://www.whitehouse.gov/the-press-office/2014/09/10/statement-president-isil-1.

Palmer, Glenn, Vito D’Orazio, Michael Kenwick, and Matthew Lane. 2015. “The MID4 Data Set: Procedures, Coding Rules, and Description.” Conflict Management and Peace Science 32 (2): 222–42.

Pettersson, Therése, and Peter Wallensteen. 2015. “Armed Conflicts, 1946-2014.” Journal of Peace Research 52 (4): 536–50.

Wilkenfeld, Jonathan, and Michale Brecher. 1984. “International Crises, 1945-1975: The UN Dimension.” International Studies Quarterly 28 (1): 45–67.