Choosing to Intervene: Outside Interventions in Internal Conflicts

Recent scholarly and policy attention has been devoted to understanding outside interventions in civil conflicts. Using a decision theoretic model to develop the constraints faced by decision makers, I derive hypotheses about the conditions under which we would expect to observe outside military or economic interventions in civil conflicts. These hypotheses are then tested against data on intrastate conflicts and associated interventions during the post-World War II period. The evidence suggests that both domestic and international considerations influence the decision to intervene, with highly intense conflicts being unlikely to attract outside actors and those with humanitarian crises quite likely to do so. A confounding result suggests that the greater the number of shared borders, the less likely will be an outside intervention.