Marius Mehrl

How do disasters affect interstate conflict? Existing perspectives on this question propose conflict-reducing or conflict-inducing effects, attribute these effects to different theoretical mechanisms and implicitly study either short- or medium- to long-term post-disaster periods. We focus on the Greek-Turkish rivalry dyad, and the 2023 Kahramanmaraş earthquakes, to collect, develop observable implications for and test these competing perspectives. Using an interrupted time series design, we analyse fine-grained monthly data on bilateral political tensions spanning the period 2009–2025. Our findings show a dramatic drop in tensions – reaching a 15-year low – immediately following the earthquakes. While this effect proved temporary, as tensions have increased since, they remain well below pre-disaster levels almost 3 years after the earthquakes struck. Probing the mechanisms behind this reduction in conflict, we document evidence that is more consistent with optimistic accounts of solidarity-based rapprochement than alternative explanations, such as strategic avoidance of diversionary conflict, resource constraints or regularised disaster cooperation. These results provide new insights into the relationship between disasters and interstate conflict, offering a cautiously optimistic addition to research on disaster diplomacy and crisis-induced cooperation in international relations.

Autocrats use secret police to stay in power, deterring and suppressing opposition to their rule. Existing research suggests that secret police succeed at this but also that they are not as ubiquitous as one may assume. We thus explore under which conditions secret police emerge in dictatorships. We develop a theoretical framework for potential predictors and apply statistical variable selection techniques to identify which of several candidate variables extracted from the literature on state security forces and authoritarian survival hold explanatory power. Our results suggest that secret police are more likely to emerge where rulers face structural, regime-external threats, such as organized anti-system mobilization and international rivals, witness successful regime-internal contestation abroad, and have sufficient material resources and personalized power to establish such organizations. This research contributes to our understanding of autocrats’ institutional choices and authoritarian politics.

Many countries allow external citizens to vote from abroad. But while research has explored when external citizens can, and actually choose to, take up this transnational practice, little research investigates who external citizens vote for , centring almost exclusively how they differ from voters in the country of origin. We highlight two transnational drivers of external citizens’ vote choices. First, exclusion abroad should push them to engage in rejection-based transnationalism and thus increasingly support parties offering diaspora-inclusive homeland identity narratives in their country of origin. And second, transnational mobilization, specifically by state bureaucrats abroad and diaspora organizations, should shape external citizens’ votes. We test these arguments using data on all Turkish elections where external voting was possible. As theorized, we find that the ruling AKP receives more support among the diaspora in countries with more exclusionary citizenship policies and higher levels of transnational mobilization. This paper advances our understanding of transnational citizenship, external voting, transnationalism, and diaspora engagement.

While the issue of gender representation has gained increasing recognition across various academic disciplines, existing knowledge about the current state of gender representation in peace and conflict studies remains limited. This study aims to investigate gender representation in peace and conflict studies by examining a newly collected dataset of articles published in five academic journals representative of the field between 2000 and 2024. We find that, although the gender gap has not disappeared yet, it has narrowed over time. Our results show that increased collaboration, particularly across genders, appears to be an important driver of this trend. Additionally, we find evidence that gender differences in topical specialization exist in the field and that a gender gap in citation patterns exists for some of the field’s core journals. Continued efforts are needed to further improve gender representation.

Military conscription affects how countries expand political rights and fight wars, as well as their citizens' view of the state and socioeconomic outcomes. Until recently, conscription was studied in a simplified fashion, missing cases where it only applies to specific societal groups. We introduce the Ethnic Military Recruitment (EGMR) data, which allows investigating selective conscription at the level of affected societal groups. The dataset is the first source providing global, systematic group‐level military recruitment data for all countries that implemented conscription over the 1946–2010 period. We explain how the data were coded, describe the landscape of selective military conscription over the period of observation and begin to assess its correlates at both country and group levels. The EGMR data offer new pathways for research on the causes and consequences of ethnic groups' societal inclusion, as well as civil–military relations, colonial legacies and civil conflict.

What is the effect of arming on conflict? While a large literature debates this question, most existing research ignores that the majority of states are unable to arm themselves and must rely on arms transfers to acquire weapons. But even where studies investigate such external arming, existing findings are mixed: arming is found to either increase, decrease, or not affect the probability of conflict onset between states. In light of this, we present a theory of external arming that conceptualizes arms transfers not simply as material capability boosts, but also as carriers of information and as relational linkages to arms suppliers. We develop several hypotheses positing external arming and conflict to be linked both negatively and positively, depending on whether recipients gain new information from arms transfers and on the nature of the suppliers. Empirical tests using additive and multiplicative effects network models and data from the Interwar years, a historical period where our information-based theory of external arming is particularly applicable, provide support for these expectations. This research advances our under- standing of how arming affects interstate conflict, unifies the disparate findings reported in previous research on external arming, and highlights the importance of the relational in International Relations.

Governmental and nongovernmental organizations have increasingly relied on early-warning systems of conflict to support their decisionmaking. Predictions of war intensity as probability distributions prove closer to what policymakers need than point estimates, as they encompass useful representations of both the most likely outcome and the lower-probability risk that conflicts escalate catastrophically. Point-estimate predictions, by contrast, fail to represent the inherent uncertainty in the distribution of conflict fatalities. Yet, current early warning systems are preponderantly focused on providing point estimates, while efforts to forecast conflict fatalities as a probability distribution remain sparse. Building on the predecessor VIEWS competition, we organize a prediction challenge to encourage endeavours in this direction. We invite researchers across multiple disciplinary fields, from conflict studies to computer science, to forecast the number of fatalities in state-based armed conflicts, in the form of the UCDP ‘best’ estimates aggregated to two units of analysis (country-months and PRIO-GRID-months), with estimates of uncertainty. This article introduces the goal and motivation behind the prediction challenge, presents a set of evaluation metrics to assess the performance of the forecasting models, describes the benchmark models which the contributions are evaluated against, and summarizes the salient features of the submitted contributions.

Substantive research in the Social Sciences regularly investigates signed networks, where edges between actors are positive or negative. One often-studied example within International Relations for this type of network consists of countries that can cooperate with or fight against each other. These analyses often build on structural balance theory, one of the earliest and most prominent network theories. While the theorization and description of signed networks have made significant progress, the inferential study of link formation within them remains limited in the absence of appropriate statistical models. We fill this gap by proposing the Signed Exponential Random Graph Model (SERGM), extending the well-known Exponential Random Graph Model (ERGM) to networks where ties are not binary but positive or negative if a tie exists. Since most networks are dynamically evolving systems, we specify the model for both cross-sectional and dynamic networks. Based on hypotheses derived from structural balance theory, we formulate interpretable signed network statistics, capturing dynamics such as “the enemy of my enemy is my friend”. In our empirical application, we use the SERGM to analyze cooperation and conflict between countries within the international state system. We find evidence for structural balance in International Relations.

The composition of the armed forces is, by now, well established as a major factor determining the risk of coups d’état. However, military discontent not only manifests in the form of coups but also as mutinies. This latter form of troop rebellion has received little empirical attention. We examine how the practice of recruiting foreigners into the armed forces affects the likelihood of such events and develop two arguments regarding a direct and a moderating effect of legionnaires on mutiny risk. First, we contend that the recruitment of legionnaires is likely to cause material-based grievances, hence be perceived as detrimental to the corporate interests, wages, and promotion prospects of the rank-and-file, and thus troops will oppose the introduction of such recruitment policies. We hence expect the onset of legionnaire recruitment policies to be associated with an increased risk of mutinies. However, once such policies are in place, the presence of legionnaires can mitigate the effects of other mutiny drivers as foreign recruits impede local soldiers’ task-related grievances and thus incentives to mutiny in reaction to them. Using global data over the period 1948–2015, we find empirical support for the expectations derived from both arguments.

Political science and international relations have undergone substantive internationalisation over the last 25 years. This short article uses a dataset covering all papers published in the British Journal of Politics and International Relations to investigate how authorship in the journal has changed over time in light of this. It finds that while, overall, BJPIR has been dominated by authors based at institutions in the United Kingdom, the journal has clearly internationalised over the past 10 to 15 years. This internationalisation has mostly been driven by increasing numbers of authors based at European institutions whereas work by authors from outside Europe, North America, and Oceania remains relatively rare. These results provide insights into the journal’s development over the past 25 years, but also the extent and the limitations of the internationalisation of political science and international relations more generally.