The argument that cultural similarity between states encourages cooperation has generally been accepted with little qualification. This article draws on established literature to highlight an overlooked but important condition for the influence of cultural similarity on interstate interaction: all else equal, states with clear and salient cultural identities are more able and willing to utilize cultural similarity as a platform for foreign policy action. The test of this argument uses the World Religion Project and Correlates of War Alliance datasets on religious composition and interstate security alliances, respectively. Results provide qualified support for religious similarity as playing a greater role in determining alliance partnerships between states with relatively high religious homogeneity.

The dissertation sheds light on the strategic calculation driving Nonstate Armed Groups’ (NAGs) behavior during and after civil conflicts. Scholars of conflict and peace research have studied mainly the relationships between governments and opposition, viewing the latter as a unitary actor. Since most civil conflicts include more than one NAG, many questions regarding civil conflict dynamics remain a puzzle. By disaggregating opposition groups in civil conflicts and considering the differences and similarities among NAGs, this project contributes to a more robust understanding of the nuances in civil conflict and post civil conflict dynamics. I ask and propose answers to three main questions in this project. In the first chapter, I examine the determinants of conflict and cooperation between NAGs in a conflict. Which factors increase the likelihood of conflict between them? And under which conditions will they cooperate with each other? While current literature debates motivations for conflict and cooperation between NAGs separately from each other, I demonstrate that mutual identity and interests incentivize NAGs to interact with each other, regardless of the nature of the interactions. NAGs are more likely to cooperate if they share mutual interests, but also to fight each other under similar conditions. I argue that NAGs carefully choose their interaction partners to signal their preferences to domestic and external audiences and are indifferent between the type of interactions. After discussing the determinants of relations between NAGs, in the second chapter I examine the effect of these relations on civil conflict duration. I argue that when the warring parties are able to signal to each other consistent behavior of conflict and cooperation, commitment problems are reduced and eventually result in shorter civil conflicts. The signal actors send to each other are captured by the concept of network balance. I demonstrate that when network balance increases, alongside rebel military capabilities, civil conflicts are more likely to terminate. The third chapter examines NAGs’ strategic behavior in post conflict settings. NAGs continue to receive support from external actors after conflict termination. I distinguish between the identity of the supporter and the types of received support, and show that when NAGs receive military types of external support civil conflicts are more likely to recur. The identity of the provider of the external support, on the other hand, does not have any effect on civil conflict recurrence. The theoretical arguments and empirical analyses of this dissertation extend beyond the particular questions examined here. The disaggregated approach emphasizes the nuances between the different parts of the opposition in civil conflicts and furthers our understanding of civil and post civil conflict dynamics. It highlights the necessity to open the “black box” of opposition and treat NAGs as individual actors. Beyond extending our theoretical understanding of civil conflicts, this work provides essential tools for policymakers in deciding on efficient intervention methods in civil conflicts. Hopefully, the dissertation does not only explain armed groups’ behavior in civil conflicts, but also sheds new light on how civil conflicts can be shortened and how peace can be sustained.