A peacekeeping mission is a UN-mandated force sent to supervise various aspects of a negotiated treaty or ceasefire between belligerents in a conflict. Since 1948 almost 130 nations have contributed military and police personnel to peacekeeping missions.
These forces vary in size and scope from a classically armed force deployed as an enforcement arm of the peace process to lightly armed observer missions deployed in support of a peace treaty or ceasefire negotiations. Peacekeeping operations are often supervised by the Security Council. The classical peacekeeping model is based on the principles of consent by host State(s), non-use of force beyond self-defence, and impartiality.
The classic UN peacekeeping model has evolved over the years to allow for more specialized mission deployments such as human rights monitoring, mine clearance and civil protection. The evolving nature of these operations has led to new challenges for peacekeepers. In particular, the possibility that a force could be subjected to allegations of violations of humanitarian law has posed a significant challenge for these operations. Such allegations can be made against the entire force or individual soldiers. However, recourse is rare given the overall immunity that peacekeeping enjoys under international law.
In addition to the general challenges of the work environment for military and police personnel on a peacekeeping mission, the stresses can be compounded by the fact that such operations typically require the presence of a force for an extended period of time, sometimes years. This may lead to fatigue. Moreover, the fact that a peacekeeping operation is an observation mission may mean that the personnel are often bystanders to horrific atrocities such as those committed in Rwanda and Srebrenica (the massacre of nearly all males in these two Bosnian cities). The experience of witnessing and being unable to act is described as double helplessness.