Does United Nations peacekeeping protect civilians in civil war? Civilian protection is a primary purpose of UN peacekeeping, yet there is little systematic evidence for whether peacekeeping prevents civilian deaths. We propose that UN peacekeeping can protect civilians if missions are adequately composed of military troops and police in large numbers. Using unique monthly data on the number and type of UN personnel contributed to peacekeeping operations, along with monthly data on civilian deaths from 1991 to 2008 in armed conflicts in Africa, we find that as the UN commits more military and police forces to a peacekeeping mission, fewer civilians are targeted with violence. The effect is substantial-the analyses show that, on average, deploying several thousand troops and several hundred police dramatically reduces civilian killings. We conclude that although the UN is often criticized for its failures, UN peacekeeping is an effective mechanism of civilian protection.

While United Nations peacekeeping missions were created to keep peace and perform post-conflict activities, since the end of the Cold War peacekeepers are more often deployed to active conflicts. Yet, we know little about their ability to manage ongoing violence. This article provides the first broad empirical examination of UN peacekeeping effectiveness in reducing battlefield violence in civil wars. We analyze how the number of UN peacekeeping personnel deployed influences the amount of battlefield deaths in all civil wars in Africa from 1992 to 2011. The analyses show that increasing numbers of armed military troops are associated with reduced battlefield deaths, while police and observers are not. Considering that the UN is often criticized for ineffectiveness, these results have important implications: if appropriately composed, UN peacekeeping missions reduce violent conflict.

Third-party states consider the regional destabilization consequences of civil wars when deciding to intervene. However, previous work implicitly assumes that potential interveners base their intervention decisions solely on their links to the civil war country. This approach is unlikely to reflect the regional concerns of interested parties. When a civil war is increasingly likely to infect its surrounding region, potential interveners with strong interests in those states neighboring the conflict will be more likely to intervene to contain the violence. Thus, relationships outside the civil war state-intervener dyad are causally associated with intervention. To test these arguments, the author accounts for the contagious properties of civil wars and the regional interests of third parties, constructing dynamic measures to represent the contagion threat posed to third party regional interests. Analyses of these measures support the argument that third parties are increasingly likely to intervene as the risk of diffusion increasingly threatens their regional interests.