This article introduces the Issue Correlates of War Identity Claims Dataset. An identity claim occurs when two states diplomatically contest the treatment of an ethnic group that both states share. A state that advances such a claim (i.e. the challenger) demands that the other state (i.e. the target) either: (i) change its domestic treatment of the group, (ii) grant the group independence, or (iii) allow the group to reunite with the challenger state (i.e. irredentism). Our research locates all known instances of identity claims throughout the world from 1946 to 2021 ( n = 111; 45 ongoing as of 31 December 2021). We first highlight the differences between these data and what appears in various existing datasets. We then elaborate on our data generating and coding processes, before descriptively presenting some of the dataset’s noteworthy characteristics (e.g. frequency over time and across regions; the most common challengers, targets, and ethnic groups involved; and claim militarization rates). Finally, we conclude with a discussion about promising ways to use the data in future research.

Abstract The International Studies Association’s (ISA) Scientific Study of International Processes (SSIP) section is dedicated to the systematic analysis of empirical data covering the entire range of international political questions. Drawing on the canons of scientific inquiry, SSIP seeks to support and promote replicable research in terms of the clarity of a theoretical argument and/or the testing of hypotheses. Journals that have been most likely to publish SSIP-related research include the top three general journals in the field of political science: the American Political Science Review, American Journal of Political Science, and Journal of Politics. A number of more specialized journals frequently publish research of interest to the SSIP community, such as Conflict Management and Peace Science, International Interactions, International Organization, International Studies Quarterly, Journal of Conflict Resolution, and Journal of Peace Research. Together, these journals published a total of 1,024 qualifying articles between 2003 and 2010. These articles cover a wide range of topics, from armed conflict and conflict management to terrorism, international political economy, economic development or growth, monetary policy, foreign aid, sanctions, human rights and repression, international law, international organizations/institutions, and foreign policy attitudes and beliefs. Data users who are interested in conducting their own research must: choose the most appropriate data set(s), become familiar with what the data set includes and how its central concepts are measured, multipurpose data sources, investigate missing data, and assess robustness across multiple data sets.

This article describes the first complete release of the Issue Correlates of War (ICOW) Territorial Claims dataset, which covers all interstate territorial claims between 1816 and 2001. Territory can have substantial tangible and intangible value for states, and competing claims for control of territory represent one of the leading sources of interstate conflict. The dataset identifies 843 territorial claims and includes measures of the salience of the claimed territory, as well as details of the militarization and ending of each claim. Beyond a discussion of the structure and contents of the dataset and the coding procedures that were used to generate it, this article also presents descriptive analyses of the dataset. These analyses highlight important patterns across time and space, including changes in the prevalence, frequency of initiation, salience, militarization, and resolution of territorial claims. Notable patterns include recent declines in the frequency with which claims tend to become militarized and a lower prevalence of tangible salience measures such as natural resources. The regional distribution of claims has also shifted markedly over time, from a historical concentration in Europe towards Asia, where by 2001 claims were far more prevalent than in any other region. The article concludes with suggestions for future research.

The Issue Correlates of War (ICOW) research project began nearly 20 years ago by collecting data on territorial claims in South America. Since then, the ICOW territorial claims dataset has expanded to cover the entire world, while ICOW has collected new data on river claims and maritime claims and is beginning a new project on identity claims. This article discusses the development and expansion of ICOW data, illustrating how the additional datasets offer important new information and open up new avenues for scholarship.

Territorial issues have been prominent causes of armed conflict and war in the modern era. This observation has led to a rapidly growing body of academic literature on the sources, management, and consequences of such issues. Although territory has gotten most of the scholarly attention, this literature has its roots in research on contentious issues that began in the 1960s. Academic research on contentious issues began with studies on issue areas in foreign policy analysis, focusing on such questions as how the foreign policy process differs from more traditional domestic policy processes. This line of research struggled to find mainstream acceptance until scholars began adopting a more substantive conception of issues, focusing on the nature of the values at stake. General patterns of foreign policy conflict and cooperation have been found to differ substantially across different issues. Importantly, territorial issues are the most frequent and most dangerous issues in armed conflict and war, leading scholars to focus much of their issue-related research on the dynamics of territorial contention. Research on territory has stemmed from the main elements of issues theory that were developed earlier: issue salience, or the importance of the issue under contention; issue context, or recent interactions over the same issue; and institutional context, or the extent to which other actors and institutions are able to influence contention over this type of issue. Armed conflict is much more likely when the issue at stake is more salient, particularly when this salience involves intangible dimensions such as the presence of a state’s ethnic kin in the claimed territory. Greater issue salience also increases the likelihood of peaceful negotiations and nonbinding conflict management techniques like mediation. A recent history of armed conflict or failed negotiations over an issue increases the likelihood of armed conflict, bilateral negotiations, and nonbinding management. The normative and institutional context also appears to affect the likelihood of conflict and peaceful management over issues, although more remains to be done in this area. The issues literature is beginning to make important strides beyond this initial work on territorial claim management. Scholars are beginning to geocode data on international borders, raising important potential benefits for the study of territory and perhaps other issues. International legal arguments appear to affect the management of territorial claims in systematic ways, and ending territorial claims seems to produce substantial improvements in relations between the former adversaries. The same general patterns seem to hold for river and maritime issues, as well as territorial issues, and these other issue types have more promising institutional contexts. Future research could benefit from considering additional issue types (including a recent effort to collect data on identity claims), as well as studying domestic and interstate issues.

Many states involved in territorial claims use the presence of their countrymen in the territory to justify their demand for sovereignty. While this can be a strong argument, the presence of these kin can also complicate settlement of the claim, as the countrymen try to rally opposition to any agreement that might transfer part or all of the territory. We examine the impact of local residents in a claimed territory on the management and settlement of the claim. We suggest that claimant states will go to greater lengths to gain/keep sovereignty over a territory that includes their countrymen, leading to a greater likelihood of armed conflict and a smaller chance of peaceful diplomatic settlement than in other claims. We find empirical support for most of these hypotheses using the ICOW territorial claims data set.

We examine the outbreak and militarization of territorial claims over ethnic groups that are shared between nation-states, emphasizing characteristics of the shared group and the strength of the global territorial integrity norm. We find that irredentist territorial claims are more likely to begin and to be militarized when the challenger state's leaders can gain politically: when the group makes up a majority of the population, soon after one or both states achieved independence, and when the group is disadvantaged politically in the target state (particularly soon after the group's status worsens). Irredentist claims are less likely to begin or to be militarized when the global territorial integrity norm is stronger. We conclude with suggestions for research to improve our understanding of the linkage between shared ethnic groups and interstate conflict.

We present lessons and best practices for conflict data collection from the experiences of the ICOW project. Lessons include the development of a search strategy for potential events, the consultation of a broad range of sources, and recognition of the limitations of these sources. More general best practices address the development of detailed instructions for coders, detailed descriptions for data users, and strategies for managing research assistants and preserving project documentation.

Two primary mechanisms for managing competitive interstate claims to maritime areas are evaluated: the creation of private ownership of maritime zones in the form of Exclusive Economic Zones (EEZs) and the creation of a global institution, the United Nations Convention on the Law of the Sea (UNCLOS), to establish standards for maritime claims and dispute resolution procedures. Analyses of maritime claims in the Western Hemisphere and Europe from 1900 to 2001 show that declared EEZs help states reach agreements over maritime conflicts in bilateral negotiations, while membership in UNCLOS prevents the outbreak of new maritime claims and promotes third-party management efforts of maritime conflicts. Neither mechanism influences the probability of militarized conflicts over maritime areas.

This paper attempts to learn from the past two centuries of territorial claims to make projections about the most dangerous claims in today's world. These projections are based on an analysis of preliminary data on territorial claims across the world since 1816, as collected by the Issue Correlates of War (ICOW) project. Characteristics of each claim (such as strategic or economic value of the claimed territory, ethnic/identity ties between each claimant and the territory's inhabitants, and recent militarization of the claim) and of the claimants (such as relative capabilities and joint democracy) are used to draw lessons about the most conflict-prone situations. These lessons are then used to make projections about the claims that remain ongoing today, in order to predict which are most likely to experience serious armed conflict. The paper concludes with a discussion of the findings' relevance for policymakers, an important direction that political scientists would do well to consider in our research. Territory has been a leading source of conflict for centuries (e.g., Holsti 1991; Vasquez 1993; Hensel 1996, 2012; Huth 1996). Territorial sovereignty has been involved in around one third of all armed conflict in the past two centuries, as well as a majority of all full-scale wars since 1648. Conflicts over territory are also more likely to escalate to serious levels than conflicts over other issues, particularly when the territory at stake is more valuable. Somewhat surprisingly, though, quantitative scholars of international conflict have made relatively little effort to discuss the implications of their findings for policymakers. While many quantitative studies conclude with an obligatory paragraph hinting at a few ideas that policymakers could consider, little effort is devoted to presenting these suggestions in a format that policymakers could actually understand (if, indeed, they actually came across the article). This has led to political criticism of research funding for the social sciences and repeated efforts to end National Science Foundation (NSF) funding for Political Science research, culminating in the 2013 congressional limitation of NSF Political Science funding to research that is certified as "promoting the national security or the economic interests of the United States." While critics of this limitation responded by highlighting a number of studies funded by NSF that had made just such a contribution, it seems clear that such work has not gotten the attention of policymakers. The current project represents the beginning of an effort to draw policy-relevant conclusions from the Issue Correlates of War (ICOW) research project, and to present those conclusions in a format that is accessible to those without high-powered training in quantitative methodology. This project begins by attempting to identify all territorial claims, or explicit

Although territorial claims have been receiving an increasing amount of scholarly attention, few studies have examined the impact of territorial claims on other phenomena. In this paper we study the impact of territorial claims on bilateral trade. We expect that an ongoing conflict over territory should serve as an obstacle to bilateral trade, but after the claim is resolved, trade will increase. We find support for this argument, with trade increasing substantially after a dyad's last territorial claim is settled, regardless of the way that the claim was settled. We conclude by discussing ways for future research to extend beyond this very preliminary study.

While geographic proximity is widely regarded as making armed conflict more likely, I argue that the impact of proximity depends on the status of the border between two states. Conflict should be most likely between two states (holding proximity constant) while they have unresolved territorial claims. But once those claims are resolved, conflict -even over non-territorial issues -should be less likely than before, particularly when the claims were resolved definitively through an agreement or military action. These expectations are supported by the conflict behavior of states in the Americas and Western Europe. ''We can change history but not geography. We can change our friends but not our neighbors. We have seen hostility for years. Now friendship must be given a chance.'' --Atal Behari Vajpayee, Prime Minister of India (22 February 1989) International relations scholars have long recognized a connection between borders and armed conflict. Research in the 1960s and 1970s showed that states with more borders tend to experience more conflict, and more recent work on individual borders shows that neighbors are much more conflict-prone than more distant states. Yet a nation-state's neighbors change only infrequently, which makes it difficult for borders to explain such time-varying phenomena as militarized conflict. This paper explores the changing relationship between borders and armed conflict, focusing on contention over the border itself. While the border itself is under contention between two neighbors, they should be relatively more likely to experience high levels of conflict, but conflict levels should be reduced greatly once the border is resolved. This paper investigates this expectation using nearly two centuries of history in the Americas and Western Europe, and finds strong support. Armed conflict between neighbors is most likely while territorial claims are ongoing; once all territorial claims are resolved, states generally experience a sharp dropoff in conflict over even non-territorial issues. The paper concludes with a number of suggestions for improvements or extensions beyond these admittedly preliminary analyses. Theoretical Development International borders have been recognized as contributing to armed conflict

Rising demand for water in water-scarce areas has led to frequent predictions of looming “water wars,” although evidence suggests that water is also an important source of cooperation. This paper follows up on recent research suggesting that river disagreements are more likely to lead to both militarized conflict and peaceful negotiations when water demands and water scarcity are greatest, but that river treaties have generally prevented militarization while increasing negotiations. Here, we examine the effectiveness of these negotiations, in order to determine whether factors that promote negotiation onset have different effects on negotiation outcomes. Empirical analysis suggests that negotiations are most likely to succeed when they concern rivers with high value for the negotiating states (with many uses offering the possibility of negotiating tradeoffs), when they concern a current rather than future problem, and when the adversaries share closer overall relations, but less likely when water scarcity is more acute and when they involve a cross-border river with a stronger upstream state.