Why Do States Fight Some Secessionists but Not Others? The Role of External Security

Abstract Secessionist wars are considered one of the most important sources of violence in international politics. Scholars studying why states adopt coercion or concessions against secessionists have only pointed to domestic factors, such as ethnic heterogeneity or political institutions. By contrast, I argue that state strategy is determined by the external security implications of the secessionist movement. Because secession entails a large and rapid shift in the international balance of power, it generates a commitment problem: Only a state sanguine about future threats can be conciliatory to separatists. Conversely, if the state fears war after border changes, either against the seceded state due to deep identity divisions with the ethnic separatists, or an existing regional adversary due to the war-proneness of its neighborhood, it will adopt coercion. If states choose to coerce, their calibration of violence depends on secessionists’ external support; for materialist and emotional reasons, the more third-party support, the more violent the state. Using data from more than 110 interviews, diplomatic papers, and news archives, I test the theory first by contrasting Czechoslovakia's Velvet Divorce with Israeli intransigence on Palestinian statehood at Oslo, an outcome existing theories would not predict, and then by examining internal variation in India, the country most beset by separatism, across three states in the 1980s: Assam, Punjab, and Jammu and Kashmir.