International politics by other means: External sources of civil war

The literature on civil wars has recently turned towards their international context but lacks an account for how conflict beyond a state’s borders contributes to civil war onset. I argue that interstate rivalries can increase the risk of civil war in other states when rivals come to associate the foreign-policy orientation of other states with their own security. I present three pathways through which rivals increase the risk of civil war in other states. First, competition between rivals creates a ratchet effect by which the prospect of one’s involvement in a conflict makes it more likely that the other becomes involved. This dynamic makes support easier to secure and lowers the expected costs of war for governments and opposition groups. Second, rivals encourage domestic polarization as parties attempt to capture their influence, making domestic conflicts more intractable. Third, uncertainty over the potential for intervention by rivals increases the risk of miscalculation. I test the implications of the theory with novel spatial measures of interstate conflict and rivalry. Using logistic regressions and random forests, I find that being in the neighborhood of interstate rivals can increase a state’s risk of civil war.