Peace enforcement is the use of military force to compel peace in a conflict, generally against the will of combatants.^[1] This usually requires more military force than peacekeeping operations. The United Nations, through its Security Council per Chapter VII of its charter, has the ability to authorize force to enforce its resolutions and ceasefires in force.^[2][3]

Peace enforcement differs from peacekeeping in that peace enforcement activities are generally used to create a peace from a broken ceasefire, or to enforce a peace demanded by the United Nations.^[1][2] Peace enforcement requires more military force than peacekeeping, and is consequently best carried out by heavily armed forces.^[1] However, it is generally unable to create lasting peace, as it does nothing to deal with the underlying problems which caused the conflict.^[4]

Perhaps the two most prominent examples of peace enforcement are the Korean War and the Gulf War. In both cases, a country invaded another as part of an illegal war of aggression, only to be repulsed by a US-led UN military coalition.^[2]

A report on peacekeeping and peace enforcement in the 1990s for the United States Army specified this difference between peace enforcement and peacekeeping:

Peacekeeping, a role the U.N. has played over the years, is relatively straightforward and, despite its difficulties, comparatively easy. Peacekeeping involves monitoring and enforcing a cease-fire agreed to by two or more former combatants. It proceeds in an atmosphere where peace exists and where the former combatants minimally prefer peace to continued war. Peace-enforcement, as it is used by the United States Joint Chiefs of Staff, entails the physical interposition of armed forces to separate ongoing combatants to create a cease-fire that does not exist. Boutros-Ghali, on the other hand, uses the term to refer to actions to keep a cease-fire from being violated or to reinstate a failed cease-fire. It is a subtle difference, but it does imply the existence of some will for peace. The American version more realistically portrays another, far more difficult matter. By definition, in a situation for which peace-enforcement is a potentially appropriate response, war and not peace describes the situation, and one or more of the combatants prefer it that way. This means that, unlike peacekeepers, peace enforcers are often not welcomed by one or either side(s). Rather, they are active fighters who must impose a cease-fire that is opposed by one or both combatants; in the process, the neutrality that distinguishes peacekeepers will most likely be lost.^[5]