Since the end of the Cold War, the United States has intervened in the affairs of sovereign states on several occasions by using military force. A combination of humanitarian sentiments and practical policy considerations motivated both Democratic and Republican presidents to become involved in civil wars and humanitarian crises. These interventions met with mixed results, and even the most successful missions encountered serious problems. Improving the conduct of such interventions requires understanding these past operations as well as considering conflicts in which the United States chose not to intervene.This Letort Paper covers U.S. military interventions in civil conflicts since the end of the Cold War. It defines intervention as the use of military force to achieve a specific objective (i.e., deliver humanitarian aid, support revolutionaries or insurgents, protect a threatened population, etc.) and focuses on the phase of the intervention in which kinetic operations occurred. The Paper considers five conflicts in which the United States intervened: Somalia (1992-93), Haiti (1994), Bosnia (1995), Kosovo (1999), and Libya (2011). It also reviews two crises in which Washington might have intervened but chose not to: Rwanda (1994) and Syria (2011-12). The author examines each case using five broad analytical questions: 1. Could the intervention have achieved its objective at an acceptable cost in blood and treasure? 2. What policy considerations prompted the intervention? 3. How did the United States intervene? 4. Was the intervention followed by a Phase 4 stability operation? 5. Did Washington have a viable exit strategy?Answering these questions reveals distinct patterns in U.S. interventions. Despite their frequent reference to American values, Presidents have rarely intervened on purely humanitarian grounds. Some strategic interest usually underlay even the most seemingly altruistic missions. Although they had the means to intervene unilaterally, every administration sought international approval for intervention and usually entered a threatened state as part of a coalition, often one made up of North Atlantic Treaty Organization allies. Whenever possible, the United States sought to intervene with airpower alone. It avoided deploying ground troops, and when it did so, made sure that those forces operated under robust rules of engagement with rigorous force protection pursuing limited objectives unlikely to cause casualties. A United Nations Peacekeeping Mission usually followed American interventions, and the Pentagon always insisted that developing a viable exit strategy be part of the planning process for each mission, although this requirement was not always met.From the patterns evident in past campaigns lessons to inform the conduct of future missions can be derived. The United States should only intervene when doing so has a reasonable chance of success. When intervention becomes necessary, the White House should seek international approval and operate as part of a coalition or alliance with airpower being its primary contribution. If it must deploy ground troops, it should keep the American footprint small and withdraw forces as soon as possible.