The UN has been in the business of peacekeeping since 1948. During the Cold War, UN missions were mostly restricted to placing lightly armed observers between warring states to monitor compliance with cease-fire agreements. Since the fall of the Soviet Union, however, more UN operations have been set up to implement comprehensive settlements to resolve civil wars and rebuild political systems, sometimes from scratch: from complex peace operations in Cambodia, El Salvador, Mozambique, and Namibia in the early 1990s to the even more complex administration of collapsed territories, such as Kosovo and East Timor in the late 1990s. Today, the UN manages 17 operations on four continents, with more than 70,000 military, police, and civilian personnel drawn from more than 100 countries. A new complex operation in Sudan is in the works, and the UN's role in Iraq may expand.
One of the UN's most difficult challenges has been to translate general lessons from those disparate experiences into a blueprint for rebuilding war-torn societies. Three accomplished political scientists believe they might have found a way to do so. In At War's End, a survey of how war-torn countries that have hosted UN peace operations in the 1990s have fared, Roland Paris concludes that, although most are still at peace, few are fully democratic and prosperous. He believes that more intrusive UN operations, including those that temporarily take over a state's administration, are the best way to ensure that liberal democracies will emerge from war. Kimberly Zisk Marten also endorses the values of liberal democracies, but in Enforcing the Peace: Learning From the Imperial Past, she claims it is a "pipe dream" to think that international administrators can bring them to war-torn societies. Calling for a much less ambitious type of international intervention, which she terms "security-keeping," Marten argues that international missions should confine themselves to maintaining security, allowing local actors to devise their own political and economic systems. In The Remnants of War, John Mueller presents a third model for the future of international peacekeeping: "