From traditional peacekeeping …

United Nations peacekeeping initially developed during the Cold War era as a means to ease tensions and help resolve conflicts between States by deploying unarmed or lightly armed military personnel from a number of countries, under UN command, between the armed forces of the former warring parties. Peacekeepers could be called in when the Security Council tasked the UN with observing the ceasefires or separation of forces arrangements in order to maintain international peace and security, as envisaged by the UN Charter.

Peacekeepers were not expected to fight fire with fire. As a general rule, they were deployed when a ceasefire was in place and the parties to the conflict had given their consent. UN troops observed from the ground and reported impartially on adherence to the ceasefire, troop withdrawal or other elements of the peace agreement. This gave time and breathing space for diplomatic efforts to address the underlying causes of conflict.

… to multidimensional peacekeeping

The end of the Cold War precipitated a dramatic shift in UN peacekeeping. Freed from bipolarization, the Security Council established larger and more complex UN peacekeeping missions, often to help implement comprehensive peace agreements between protagonists in intra-State conflicts. Furthermore, peacekeeping came to involve more and more non-military elements to ensure sustainability. The UN Department of Peacekeeping Operations (DPKO) was created in 1992 to support this increased demand for complex peacekeeping.

By and large, the new operations were successful. In El Salvador and Mozambique , for example, UN peacekeeping helped those countries during the transitional period to build self-sustaining peace. Some efforts failed, perhaps as the result of an overly optimistic assessment of what UN peacekeeping could accomplish. While complex missions in Cambodia and Mozambique were ongoing, the Security Council dispatched peacekeepers to conflict zones like Somalia and Bosnia and Herzegovina, where neither ceasefires nor the consent of all the parties in conflict had been secured. Some of the mandates given to those missions proved to be impossible to implement with the resources and the manpower provided. In addition, in a number of situations Member States were not ready to enforce their own decisions. The failures—most notably the 1995 massacre in Srebrenica (Bosnia and Herzegovina) and the 1994 genocide in Rwanda—led to a period of self-examination in UN peacekeeping.