Bases, Bullets and Ballots: the Effect of U.S. Military Aid on Political Conflict in Colombia

Does foreign military assistance strengthen or further weaken fragile states facing internal conflict? Aid may strengthen the state by bolstering its repressive capacity vis-à-vis armed non-state actors, or weaken it if resources are diverted to these very groups. We examine how U.S. military aid affects political violence in Colombia. We exploit the allocation of U.S. military aid to Colombian military bases, and compare how aid affects municipalities with and without bases. We use an instrument based on worldwide increases in U.S. military aid (excluding Latin America). We find that U.S. military assistance leads to differential increases in attacks by paramilitaries, but has no effect on guerrilla attacks. Aid also results in more paramilitary (but not guerrilla) homicides during election years, particularly in politically competitive municipalities. The findings suggest that foreign military assistance may strengthen armed non-state actors, undermining domestic political institutions.