• Nomikos, William G. 2025. Local Peace, International Builders: How the UN Builds Peace from the Bottom Up. Cambridge University Press.

    Local Peace, International Builders book cover

    Summary: Communal disputes over local issues such as land use, cattle herding, and access to scarce resources are a leading cause of conflict around the world. Over the coming decades, climate change, forced migration, and violent extremism will exacerbate such disputes in places that are ill equipped to handle them.

  • Nomikos, William G., Dahjin Kim, and Gechun Lin. 2025. "American Social Media Users Have Ideological Differences of Opinion about the War in Ukraine." Nature: Humanities and Social Sciences Communication.

    Donald Trump and Vladimir Putin shake hands

    Abstract: Though ideological differences have long been a ubiquitous feature of American politics, the rise of online news and social media has exacerbated divisions between groups. While existing research has documented how political preferences manifest online, relatively few studies have considered whether ideological divisions extend to discussions of foreign policy. We examine this question by analyzing nearly 2 million tweets about the war in Ukraine posted by Americans during the opening stages of the Russian invasion. We first categorize each tweet according to the user’s ideological leanings estimated by the network of political accounts they follow. Then, we apply a natural language processing model specifically designed for short texts to classify the tweets into clusters that we hand code into substantive topics. We find that the topic distributions of conservative, moderate, and liberal users are substantively and statistically different. We further find that conservatives are more likely to spread some form of misinformation and that liberals are more likely to express support for Ukraine. Our paper concludes with a discussion of the implications of our findings for the conduct of U.S. foreign policy.

  • Nomikos, William G. and Eric Stollenwerk. 2024. "More Security, More Trust? Security Perceptions as a Source of Government Trust in Post-Conflict Settings." Journal of Intervention and Statebuilding. Online First.

    Government monument in Mali capital

    Abstract: How can governments gain the trust of their citizens after civil war? Although previous work has thoroughly considered the drivers of governmental trust, we know relatively little about the role of security perceptions in post-conflict settings. Drawing on data from an original survey fielded with 2000 respondents from Liberia, we show that citizens’ security perceptions shape their trust in government. We also demonstrate that explicit attribution of security to specific institutions is key for linking more effective security governance with more trust. Our findings have significant implications for the design of security institutions and statebuilding in post-conflict settings.

  • Grossman, Allison, William G. Nomikos, and Niloufer Siddiqui. 2023. "How Do Religious Appeals Shape Intergroup Tolerance and Radicalization? Evidence from Burkina Faso." Journal of Experimental Political Science 10 (1): pp. 124-136.

    A gathering building in rural Burkina Faso

    Abstract: Recent efforts to improve attitudes toward outgroups and reduce support for extremists in violent settings report mixed results. Donors and aid organizations have spent millions of dollars to amplify the voices of moderate religious figures to counter violent extremism in West Africa, the Middle East, and South Asia. Despite this investment, we know little about whether such messaging persuades the primary recruits of violent extremist organizations: at-risk youth in fragile settings. In this paper, we consider whether pro-peace religious messaging can promote social cohesion among school-age respondents in Burkina Faso. Using a survey experiment, we find little evidence that such messages affect reported attitudes or behaviors towards religious extremism and find instead that it can have the unintended effect of increasing intolerance towards ethnic others. Our findings carry lessons about the inadvertent priming of ethnic identities that can result in a backlash effect among certain societal segments.

  • Nomikos, William G. and Danielle N. Villa. 2022. "Unintended Consequences: Reconsidering the Effects of UN Peacekeeping on State-sponsored Violence." International Peacekeeping 29 (4): pp. 551-623. Part of Forum on the United Nations at 75.

    UN council

    Abstract: This paper challenges theoretical and empirical arguments about peacebuilding effectiveness that put the state at the center of United Nations peace operations. The paper draws on evidence from the United Nations Stabilization Mission in Mali (MINUSMA) from 2013 to 2017. We argue that state-centric UN peacebuilding operations inadvertently incentivize local-level violence in post-conflict zones. We demonstrate that when the UN supports central governments it unintentionally empowers non-professionalized militaries, paramilitaries, and warlords to settle local scores. Armed violence against civilians in turn triggers a vicious cycle of reprisals and counter-reprisals. As an alternative to state-centric peacebuilding operations that incentivize local violence, We suggest that the UN should shift strategic resources away from central governments and toward UN policing, support of traditional and religious authorities, and the training of local security institutions.

  • Nomikos, William G. 2022. "Peacekeeping and the Enforcement of Intergroup Cooperation: Evidence from Mali." Journal of Politics 84(1): 194-208. Also published as Empirical Studies on Conflict Working Paper 20.

    Local painting of peace doves over map of Mali

    Abstract: Despite the abundance of evidence that peacekeeping works, we know little about what actually makes peacekeepers effective. Recent work suggesting that local agendas are central to modern conflicts make this omission particularly problematic. The article demonstrates that the presence of peacekeepers makes individuals more optimistic about the risks of engagement and the likelihood that members of out-groups will reciprocate cooperation. I use data from a lab-in-the-field experiment conducted in Mali, a West African country with an active conflict managed by troops from France and the United Nations (UN), to show that UN peacekeepers increase the willingness of individuals to cooperate relative to control and French enforcers. Moreover, I find that UN peacekeepers are especially effective among those participants who hold other groups and institutions in low esteem, as well as those who have more frequent contact with peacekeepers. Follow-up interviews and surveys suggest that perceptions of the UN as unbiased rather than other mechanisms account for its effectiveness.

  • Nomikos, William G. 2021. "Why Share? An Analysis of the Causes of Power-Sharing after Conflict". Journal of Peace Research 58(2): 248-262.

    Citizens of Iraq gather to vote at a school

    Abstract: Why do former belligerents institutionalize power-sharing arrangements after a civil war ends? The choice of power-sharing institutions shapes the nature of governance in many post-conflict settings. A better understanding of how belligerents come to choose institutionalized forms of power-sharing would thus help us explain how belligerents come to make a seemingly simple institutional choice that may have immense consequences. Existing scholarship emphasizes the nature of the conflict preceding negotiations, international actors, or state institutional capacity as critical factors for determining whether former belligerents will agree to share power or not. Yet these accounts overlook the importance of political considerations between and within ethnic groups. This article argues that elites create power-sharing institutions when the most significant threat to their political power comes from an outside group as opposed to from within their own group. That is, forward-looking and power-minded leaders of former belligerents push for the type of power-sharing at the negotiating table that affords them the greatest opportunity to influence country-level politics after the conflict has concluded in full. For elites facing competition from outside, this means securing power-sharing through institutional rules and guidelines in the settlement of the civil war to ensure that they are included in the governance of the state. By contrast, for elites fearing in-group rivals, complex governance institutions are at best unnecessary and, at worst, a significant concession to weaker opponents. I test the argument with a cross-national analysis of an original dataset of 186 power-sharing negotiations from 1945–2011. The empirical analysis suggests that elites are most likely to institutionalize power-sharing when no single ethnic group dominates politics and when most ethnic groups are unified. The quantitative analysis is complemented with illustrative examples from cases of power-sharing negotiations that offer insight into the proposed theoretical mechanisms.

  • Hunnicutt, Patrick and William G. Nomikos. 2020. "Nationality, Gender, and Deployments: Introducing the RADPKO Dataset". International Peacekeeping 27(4): 645-672.

    Map of Mali showing various UN contributions by country

    Abstract: This paper introduces the Robust Africa Deployments of Peacekeeping Operations (RADPKO) dataset, a new dataset of geocoded United Nations peacekeeping deployments. Drawing upon primary documents sourced directly from the UN covering 10 multidimensional peacekeeping operations from 1999 to 2018, RADPKO offers comprehensive monthly time-series data on UN peacekeeper deployment location by type, gender, and nationality. We describe the data collection in detail and discuss the cases and time periods missing from the data. We show that although the UN responds dynamically to conflict events in the field, deployments outside of population centres tend to be fairly homogeneous in regard to both nationality and gender. We use this data to empirically investigate the oft-posited link between deployment of peacekeepers and reductions in violence at the local level. We replicate and extend past studies but find that some previous findings are vulnerable to robustness checks, primarily due to data incompleteness. Our analysis suggests the importance of data collection transparency, management, and description to the quantitative study of peacekeeping. The data, updated annually, provides new opportunities for scholar conducting micro-level research on peacekeeping, conflict, development, governances, and related topics across subfields in Political science.

    Access the RADPKO data portal for the latest version.

  • Nomikos, William G. and Nicholas Sambanis. 2019. "What is the True Mechanism Underlying Audience Costs? Incompetence, Belligerence, and Inconsistency." Journal of Peace Research 56 (4): 575-588.

    Graph: Estimating audience costs with and without incompetence costs

    Abstract: Audience cost theory posits that concern over the nation’s reputation pushes voters to sanction leaders who make empty threats because they tarnish the nation’s honor. We question the empirical support for that theory. We show that survey vignettes in the previous experimental literature conflate audience costs generated by inconsistency and belligerence with approval losses arising from the perception that the leader is incompetent. These ‘incompetence costs’ are due to leaders not achieving audiences’ preferred outcomes. Our article contributes to the literature on audience costs by disentangling inconsistency and belligerence costs from incompetence costs, which we find are the larger component of audience costs. We also make a methodological contribution: we show that experimental designs in previous studies cannot test the different mechanisms; that previous estimates of audience costs are biased because treatments affect respondents’ beliefs about the likely outcome of policy actions; and we suggest a new experimental framework to estimate audience costs. Our results are consistent with arguments that audiences care more about policy outcomes than about leaders’ inconsistency or belligerence during a crisis.

    Accompanying guest blog post in the Duck of Minerva.

  • Marinov, Nikolay, William G. Nomikos, and Josh Robbins. 2015. "Does Electoral Proximity Affect Security Policy?". The Journal of Politics 77(3): 762-773.

    Newspapers declaring various election winners

    Abstract: How do approaching elections affect the security policy states conduct? We build on classic political economy arguments and theorize that one problem likely faced by democratic policy makers near elections is that of time inconsistency. The time-inconsistency problem arises when the costs and benefits of policy are not realized at the same time. We develop an application of the argument to the case of allied troop contributions to Operation Enduring Freedom and the International Security Assistance Force mission in Afghanistan. In that case, we argue that the expectation should be one of fewer troops committed close to elections. The exogenous timing of elections allows us to identify the effects of approaching elections on troop levels. Our finding of significantly lower troop contributions near elections is arguably the first identified effect of electoral proximity on security policy.

  • Nomikos, William G. 2013/4. "Reevaluating Foreign-Imposed Regime Change". International Security 38(3): 184-195.

    The Berlin Wall

    Abstract: Although Downes and Monten (2013) offer promising results in support of their hypotheses, two factors should make scholars skeptical of the conclusions drawn from their interpretation of the evidence. First, even though Downes and Monten duly explore the efficacy of varieties of FIRC, they omit the most critical analytical category related to the dependent variable. In evaluating the ability of FIRC to produce democracy, one should focus on cases of foreign-imposed democratization (FID) where the intervener intended to replace a nondemocratic regime with a democratic one. Second, the nature of FIRC operations has changed over time in ways unaccounted for by Downes and Monten. For historical and theoretical reasons outlined in this paper, FIRC carried out before World War I looks significantly different from FIRC carried out since 1918. A closer examination of the targets of FID after World War I reveals a fairly remarkable success rate: thirteen out of seventeen targets transitioned to consolidated democracies within ten years of the intervention (see table 1). Such a record should give us pause be fore concluding that FIRC has little or no independent effect on a state's democratization prospects.

  • Hunnicutt, Patrick and William G. Nomikos. "Peacebuilding in the Commons: United Nations Peacekeeping as Conflict Mitigation and Climate Adaptation."

    Unpol soldiers patrol a village

    Abstract: United Nations peacekeeping operations (UN PKOs) increasingly deploy in settings experiencing both violent conflict and climate change. Given this overlap, our paper presents an interdisciplinary analytical framework for understanding how UN PKOs' conflict mitigation strategies may support climate adaptation. We focus specifically on activities UN PKOs undertake to address intercommunal violence related to natural resources impacted by climate change. In short, we argue that contemporary UN PKOs reduce the risk of intercommunal violence by engaging in de-facto common pool resource (CPR) management when deployed to climate-impacted settings, helping strengthen the institutions required to cooperatively manage shared resources like water for livestock. We generate this argument inductively, relying on qualitative evidence from four multidimensional UN PKOs in the Sudano-Sahelian zone—a region where intercommunal violence is increasing, partly due to the effect of climate change on shared grazing lands. These data highlight how contemporary UN PKOs' capacities for local patrolling, building infrastructure, and mediating disputes strengthen various aspects of CPR management and subsequently reduce the risk of intercommunal violence. Overall, this study meets practitioners' calls to better capture the impact of conflict mitigation strategies on climate resilience and vulnerability.

  • Hunnicutt, Patrick, William G. Nomikos, and Rob Williams. "The Strategic Logic of Violence against UN Peacekeeping."

    A UN tank in Mali

    Abstract: Despite abundant evidence that United Nations (UN) peacekeeping operations (PKOs) promote peace in conflict settings, we know remarkably little about what explains violence against UN peacekeepers themselves. We argue that armed groups target PKOs in response to peacekeepers' interactions with civilians away from the battlefield. Contemporary PKOs act as surrogates for the state, providing civilians with governance and security in areas where the government is weak. Armed groups competing with the government for political control thus target peacekeepers where their ability to gain civilian support is greatest. Using cross-national data on attacks against UN peacekeepers deployed to Africa from 1999 to 2019, we find a robust relationship between the deployment of additional UN peacekeeping police — who frequently engage with civilians to provide security and extend the rule of law — and the targeting of peacekeepers. We explore the mechanisms underlying this relationship through a mixed-methods analysis of attacks against the United Nations Multidimensional Integrated Stabilization Mission in Mali, a critical case for understanding peacekeeper targeting. Our analysis reveals that armed groups attack the mission in areas where its police frequently patrol to integrate themselves with the civilian population, gather information about armed groups, and frustrate rebel governance.

  • Nomikos, William, Ipek Ece Sener, and Rob Williams. "The Peacekeeping Dilemma: Understanding the Challenges of Modern Peacekeeping Operations."

    Burkina Faso heat map

    Abstract: Despite an abundance of cross-national evidence that United Nations (UN) peacekeeping operations (PKOs) enhance the prospects for peace in post-conflict settings, many recent operations have failed to achieve their goals, a pattern reflected in a robust set of qualitative studies on the subject. We address this tension using a new theoretical framework and a novel empirical strategy that disentangles the causal effects of peacekeeping. We argue that peacekeepers may resolve some types of conflict while unintentionally causing outbreaks of other types of violence—a phenomenon we call the peacekeeping dilemma. We examine the case of Mali, the site of a multidimensional UN PKO from 2013 until its forced withdrawal in 2023. We employ a geographic regression discontinuity design around the border of Mali and Burkina Faso to estimate the causal effect of deploying peacekeepers. We find that UN peacekeeping reduces conflict between non-state rebel groups as well as communal violence between civilians, but not violence between governments and rebels. More troubling, we find no evidence that UN peacekeeping decreases rebel violence and may under certain conditions increase government violence against civilians.

  • Charaniya, Amaan, Jordon Newton, William G. Nomikos, and Michael Olson. "Reconstruction and Representation." Awarded Honorable Mention, Best Paper Presented at SPSA 2023.

    American south reconstruction illustration

    Abstract: Despite substantial evidence that international interventions help resolve intrastate violence, the occupations that follow them often fail to build stable democracies that facilitate out-group representation. We argue that the presence of occupying troops has meaningful short-term consequences for representation, but that democratization will fail if domestic actors do not break down conflictual social cleavages by changing norms or maintaining inclusive institutions. To test our expectations, we examine the Reconstruction period (1865-1877) in the American South following the U.S. Civil War. Our analysis uses original state legislative roll call data to measure legislators' preferences. We pair these data with detailed information on legislators and the districts they represent. We show that in several states occupation by federal troops is associated with better representational outcomes for African Americans, but that these gains did not persist beyond Reconstruction. Our results highlight the value and limitations of post-conflict occupations for facilitating democratic transitions.

  • Nomikos, William G., Amaan Charaniya, Rex Deng, Dahjin Kim, Gechun Lin, and Ipek Ece Sener. "Social Media Reactions to US Withdrawal from Afghanistan." Awarded Best Paper Presented at APSA 2022, Foreign Policy Section.

    A user scrolls through a smart phone social media app

    Abstract: The impact of social media on public discourse is well-established across various scientific fields. While previous research has considered the link between social media and international politics, the question of how foreign policy shapes social media users' opinions of political leaders remains largely unexplored. This study examines the role of social media in shaping public sentiment toward U.S. political leadership during the Afghanistan withdrawal of 2021. Using a dataset of over 7 million posts on Twitter, we analyze negative sentiment directed at the Biden and Trump administrations throughout this critical period. Our findings reveal that the initial troop deployment triggered a significant spike in negative sentiment, which persisted throughout the withdrawal, while subsequent events had little impact on public opinion. The results suggest that media coverage and the immediate response to the troop deployment drove sustained criticism, while later events did not elicit comparable reactions. These findings underscore social media's role in amplifying immediate reactions to major foreign policy events. In doing so, our study offers valuable insights for researchers across disciplines into how social media influences discourse on key social and political issues.

  • Nomikos, William G. "How peacekeeping reduces climate-induced conflicts between farmers and herders."

    Abstract: Please check back soon.

  • Abramson, Scott, David Carter, William G. Nomikos, Sarah Warren, and Romuald Anago. "Intergroup Trust and Social Networks in Fragile Settings."

    Abstract: Please check back soon.

  • Freeman, Bianca and William G. Nomikos. "Blue Line, Blue Helmet: Race and the Limits of Representation in Peacekeeping."

    Abstract: Please check back soon.

  • Kikuchi, Masanori, Melissa Lee, and William G. Nomikos. "Domestic Politics and Statebuilding: Evidence from Postwar Japan."

    Abstract: Please check back soon.

  • Moreno Gama, Laura Elizabeth and William G. Nomikos. "Discounting Tomorrow: Colombia’s Renewable Energy Ambitions Amid Conflict and Resource Struggles."

    Abstract: Please check back soon.

I have taught undergraduate courses on Climate Change and Conflict, Peacekeeping, Ethnic Conflict, and Quantitative Methods.

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