One of the most vexing issues that has faced the international community since the end of the Cold War has been the use of force by the United Nations peacekeeping forces. UN intervention in civil wars, as in Somalia, Bosnia and Herzegovina, and Rwanda, has thrown into stark relief the difficulty of peacekeepers operating in situations where consent to their presence and activities is fragile or incomplete and where there is little peace to keep. Complex questions arise in these circumstances. When and how should peacekeepers use force to protect themselves, to protect their mission, or, most...