In a recent contribution to the Journal of Conflict Resolution , Monica Toft presents new data and analysis that suggest a rise in religious civil war, and question our findings on linguistic and religious cleavages' effect on armed conflict onset. We welcome Toft’s contribution, in particular her replication of our results, and the very well documented new dataset on civil wars. Yet we disagree with several of Toft’s specific claims and raise three larger questions about the study of religion and armed conflict. First, what is the relevant counterfactual when analyzing the religion-conflict link? Second, how useful is it to classify entire conflicts as religious? Third, what is the mechanism that links religion and conflict? Revisiting her analysis and adding new empirical evidence, we show that Toft fails to undermine our earlier results and does not find support for her own theoretical mechanism of religious outbidding in the Muslim world.
When do democratically-elected leaders comply with rulings from international courts? While international courts have been studied independently, little research examines their interaction with state-level transitional justice (TJ) institutions. We evaluate the incentives of post-authoritarian leaders to comply with rulings of international courts related to violence under military dictatorships. We expect leaders to be more likely to comply with international court rulings addressing authoritarian human rights violations when maximalist TJ (domestic trials and vettings) has been implemented. In contrast, we expect leaders will be no more likely to comply when minimalist TJ (amnesties) has been adopted. Using data on remedies issued by the Inter-American Court of Human Rights from 1989 to 2020 for abuses committed under military dictatorships, we find that compliance is more likely following domestic trials and vettings but amnesties have no significant effect on the likelihood of compliance, as predicted. Overall, our results suggest that international courts serve as complements for domestic TJ.
Face-to-face diplomacy is central to international politics, yet existing research focuses largely on civilian leaders and diplomats. We introduce an original meeting-level dataset of China’s public military-diplomatic engagements from 2000–2023. Drawing on four authoritative Chinese-language party, state, and military outlets, the dataset records over 2,500 engagements involving senior Chinese military leaders and foreign counterparts. It classifies engagements as receptions in China, outbound visits, multilateral organization meetings, and defense and security fora, while preserving information on participants, timing, location, sources, and reported content. Official reporting frames these engagements primarily around cooperation and exchange. An illustrative analysis of outbound visits finds little evidence that China concentrates senior-level military outreach on U.S. allies. Outbound visits are instead positively associated with pre-existing security-specific and economic relationships with China. This dataset enables future research on how military diplomacy complements civilian diplomacy, signals strategic priorities, and shapes security cooperation, crisis management, and political influence.
Much if not most of human judgment is intuitive rather than reflective, but what types of behaviors result from non-deliberative as opposed to deliberative choice? We argue that for evolutionary reasons, intuition favors retaliatory aggression and a reliance on the deterrence model, the set of hunches that stress the importance of standing firm and demonstrating resolve to avoid challenges. By contrast, careful and analytical thought tends towards diplomacy and cooperation. By thinking from the gut and shooting from the hip, humans solved deterrence challenges in our evolutionary past. Across four studies—a time pressure experiment, an observational survey of thinking styles, a large-scale text analysis of Cold War US foreign policy elites, and a case study of US President Ronald Reagan—we find support for these expectations. These results are surprising, given that deterrence is often associated with rational deliberation. Instead, the intuitive nature of retaliatory aggression and the embrace of the deterrence model seem to be ecologically rational.
Numerous jihadist organizations pledged allegiance to al-Qaeda (AQ) or the Islamic State (IS) in recent years. How do armed groups respond to competition from transnational jihadist rivals? A prominent strand of research argues that increased competition leads armed groups to outbid rivals through violent escalation. However, an alternative theory suggests that groups can restrain their violence to distinguish themselves from extremist rivals and appeal to local and international audiences. We test these competing hypotheses surrounding outbidding and restraint using original data on pledges to AQ and IS and a Difference-in-Differences (DiD) analysis of militant violence against civilians. We find that pledges to AQ or IS are associated with a moderate decline in the violence of other armed groups against civilians. Importantly, these findings are primarily driven by non-religious organizations and groups that are not formally designated as terrorists. This study contributes to research on militant competition, civilian victimization, and transnational actors.
How does leadership turnover affect international conflict? We propose a new theory emphasizing the domestic constraints of new leaders. Leadership turnover results in successors who, regardless of their absolute strength, initially face a period of relative political vulnerability. We argue that new leaders prioritize consolidating power-through repression, co-optation, and reforms-before engaging in external conflict. Using a novel dataset of wars and rulers in 17 states during the Spring-Autumn and Warring States eras (771-221 BCE) of ancient China, we leverage exogenous variation in leadership turnover induced by rulers' natural deaths. We find that leadership turnover decreases the likelihood of initiating interstate wars. To further substantiate our theory, we present both empirical and anecdotal evidence of power consolidation strategies during leaders' early tenure. Our findings contribute to debates on the diversionary use of force and the broader role of domestic politics in shaping international conflict.
How does U.S. military education build influence among foreign officers? This study proposes two theoretical pathways from training to influence. The extrinsic pathway is based on material incentives for cooperation and acceptance of the U.S.-led hierarchy. In contrast, the intrinsic pathway relies on interpersonal networks based on trust and reciprocity expectations. The study argues for the latter: Cooperation by U.S.-trained officers occurs not out of subordination, but because they view themselves as part of a network with the U.S. The empirical analysis focuses on the case of Turkey: a NATO ally that nevertheless has a history of anti-American sentiment among the military ranks. Through both interviews and a survey experiment with Turkish officers, we provide individual-level evidence showing that U.S.-trained officers are more likely to both grant and make informal requests when dealing with U.S. counterparts, and that this effect is larger for those officers who participate in longer programs.
Why does amnesty for mass atrocities persist despite the international justice regime’s efforts to end impunity? I address this puzzle by highlighting a new dynamic in contemporary civil wars: the growing risk of international prosecution in rebel groups’ foreign sanctuaries. I argue that the international justice regime—particularly the International Criminal Court (ICC) and universal jurisdiction—undermines the security of these sanctuaries, making return under amnesty more attractive for rebel groups. This logic explains why amnesty for serious crimes persists, if not increases, despite the global norm against impunity. Large-N analyses show, first, that rebel groups operating abroad and facing international legal risk are more likely to obtain amnesty, and second, that amnesty provisions increase as prosecution risks rise in host states. The findings reveal an irony of global justice: a system created to end impunity entrenches it through amnesties, while simultaneously constraining warlords’ operational space and narrowing their strategic options.
A cross-national shift toward lower-yield nuclear weapons has generated renewed interest in the integrity of the firebreak: the conceptual barrier between conventional and nuclear warfare. We theorize that low-yield nuclear weapons alter nuclear nonuse mechanisms. They threaten to breach the firebreak by offering a more credible, but less costly, deterrent and undercut norms grounded in nuclear weapons' effects. To test the integrity of the firebreak, we conduct simultaneous survey experiments investigating how Pakistani and Indian citizens consider low-yield nuclear weapons use in an escalating crisis. We find a low-yield nuclear weapons threat to be credible, but not necessarily stabilizing. Both publics in this rivalry exhibit substantial willingness not only to issue a nuclear response to a low-yield nuclear strike, but also to introduce nuclear weapons into conflict. However, neither universally seeks retribution. Vivid information about nuclear effects moderates retaliation preferences among citizens who strongly favor their co-nationals.
Administrative boundaries play a crucial but understudied role in managing separatist conflict in federal and decentralized states. I argue that closely aligning these boundaries with ethnic settlement patterns helps sustainably defuse separatist conflicts. When minorities control unified ethnic regions, autonomy enables them to pursue their policy goals, reducing grievances. Conversely, when they are fragmented across regions or remain minorities at the regional level, autonomy is more likely to violate their aspirations and fuel continued separatist mobilization. I test this argument using new spatial data on regional boundaries in 132 multi-ethnic countries (1946-2017). A difference-in-differences design exploiting within-group variation over time reveals that administrative boundaries critically shape separatist mobilization. The step-wise implications of my hypothesized mechanisms are reflected in analyses of intermediate outcomes and in influential case accounts. These findings underscore the importance of regional boundary design in managing ethnic conflict and offer insights for institutional responses to separatist pressures.
A puzzling feature of conditional military aid is that its amount is correlated negatively with the level of its recipients' security cooperation. I propose a new explanation for the apparent failure of security assistance, demonstrating that using foreign aid as a source of income stabilisation for the recipient rationalises the inverse relationship observed between the provision of foreign aid and policy concessions. Aid conditionality is modelled as an implicit interstate agreement that specifies how a recipient allocates domestic and foreign financial resources across different security-related policy areas in an infinitely-repeated agency game. It is shown that efficient security cooperation between countries with conflicting interests involves a certain diversion of conditional assistance. I illustrate the model's logic by reference to the purported epitomes of the ineffectiveness of foreign aid as a counterterrorism tool, which are the post-9/11 security relationships between the United States and Pakistan as well as Yemen.
Natural resource price shocks intensify competition for control of windfall sites. They also prompt criminal organizations to redeploy fighters toward those windfalls, thinning their presence in other resource regions that do not share the price surge. I test this in Mexico, focusing on drug cultivation and the extortion of mining operations. Exploiting exogenous variation in global gold prices (2001-2018) in a panel of 2,444 municipalities, I find that the gold boom led to a 15 percent decrease in homicides, a 19 percent drop in cartel-related executions, and a 19 percent reduction in active cartel cells in the average heroin-producing municipality. Conversely, when U.S.-bound heroin trafficking surged, violence in gold-mining areas fell. Together, the results reveal two linked mechanisms: rapacity in windfall zones and a peace dividend in resource areas bypassed by the boom. I further show that the decline is driven chiefly by reduced inter-cartel competition, with cartel-state clashes essentially unchanged.
Does contributing troops to UN peacekeeping reduce a state's propensity for interstate conflict? While existing research examines peacekeeping's effects on host countries, troop-contributing countries' own conflict behavior remains understudied. I theorize two mechanisms: costly signaling that credibly communicates peaceful intent, and socialization through UN doctrine and multinational networks that institutionalizes restraint. Using country-year data from 1990 to 2014 and multiple measures of participation, the analysis includes controls for the security environment, including recent conflict involvement, territorial disputes, prior interstate conflict, and intrastate armed conflict. Across ordered logit, logit, and count models, supplemented by extensive robustness checks, matching, selection corrections, fixed effects, and dynamic specifications, greater peacekeeping engagement is consistently associated with lower hostility, lower initiation risk, and fewer disputes. These findings extend conventional wisdom by identifying peacekeeping as both a global public good and domestic risk-reduction strategy, redirecting institutional theory from hosts to senders and clarifying how international engagement reshapes state behavior.
Numerous countries in recent decades have formally recognized collective indigenous claims to territory and self-governance during civil conflict despite challenges to state authority and social order. How does collective indigenous recognition impact conflict violence within communities? This paper shows that indigenous recognition can shore up order and state reach. It does so in Peru, where the state recognized thousands of indigenous communities during an internal conflict from 1980 to 2000 that disproportionately impacted indigenous Peruvians. Using a staggered difference-in-difference research design and an original spatial mapping of conflict violence to indigenous communities, I find that formal recognition reduced wartime violence. Further analysis of community characteristics as well as state and community counterinsurgency efforts indicates that as recognition fosters greater legibility and transfers disputes into state institutions, it invites state penetration and coordination with state actors that ultimately adheres communities to the state.
Event datasets, such as those provided by the Uppsala Conflict Data Program (UCDP), provide high-quality data on conflict fatalities. However, such data are likely to suffer from an unknown extent of bias and uncertainties in the reports they are based on. Although a substantial literature documents reporting bias in conflict research, analyses that quantify this bias are mostly limited to single countries. Here, we combine a survey with UCDP coders and statistical modeling to derive a distribution of plausible number of fatalities given the number of battle-related deaths and the type of violence documented by the UCDP. We provide a generalizable, cross-national measure of uncertainty around UCDP reported fatalities that is more robust and realistic than UCDP's documented low and high estimates, countering UCDP's intrinsic tendency to under-estimate fatalities, and we make available a dataset and R package that can be applied to future releases of the UCDP data.
We show empirically that interstate conflicts are less likely among countries that share more of their oral tradition. Popular tales and narratives are related to expectations and beliefs about other parties' behavior, and larger cultural similarities reduce negotiation failures between states. To validate this interpretation, we show that countries with more oral tradition in common are more likely to form military alliances, more likely to participate in the same international organizations, more likely to vote similarly in the UN general assembly, more likely to trade with each other and, in case a conflicts breaks out, more likely to terminate it with a negotiation.
This article introduces a new global dataset tracking the adoption of 31 important arms technologies across all states from 1816 to 2023. Covering eight major categories - from small arms and artillery to combat helicopters and ballistic missiles - the dataset provides a comprehensive long-term view of the global evolution and diffusion of arms technology. We describe the conceptual foundations and coding procedures, as well as transformations of the final data relevant for scholars of international relations and comparative politics. We demonstrate the relevance of the data through three empirical applications: we show that arms technologies spread in ways consistent with the logic of the security dilemma; that technological superiority helps explain which states win wars, and that advanced arms help autocrats stay in power. These findings highlight the central role of arms technology in shaping both the global distribution of power and the durability of autocratic regimes.
Foreign policy making involves balancing ethical values and instrumental concerns. Do politicians and citizens differ in how they weigh these factors when directly confronted with this trade-off? Focusing on attitudes toward arms exports, we argue that citizens, but not politicians, tend to prioritize human rights concerns over the political and economic benefits for their own states. We tested these arguments in four survey experiments among citizens and parliamentarians in the United Kingdom and Germany. We presented participants with fictitious arms deals and varied the human rights records of recipient regimes as well as the benefits of arms deals to assess how these factors influence attitudes toward arms exports. While we find substantial effects of both human rights violations and benefits on support for arms exports, their interaction remains insignificant across all samples. Hence, our findings yield no evidence for an elite-public gap in weighing ethical and instrumental concerns in foreign policy attitudes.
