Peacekeeping / Peace Enforcement

Introduction / Definition: 

Peacekeeping refers to the deployment of national or, more commonly, multinational forces for the purpose of helping to control and resolve an actual or potential armed conflict between or within states. Most peacekeeping operations are undertaken with the authorization of, and are often led by, the United Nations (UN) but regional organizations may also conduct peacekeeping operations, and in some cases single states have undertaken such operations as well. Peacekeeping forces are normally deployed with the consent of the parties to a conflict and in support of a ceasefire or other agreed upon peace measures. Peacekeeping forces are therefore usually unarmed or only lightly armed and use the minimum of force necessary and then only exceptionally. Peace enforcement refers to the use of military assets to enforce a peace against the will of the parties to a conflict when, for instance, a ceasefire has failed. Peace enforcement often exceeds the capacity of peacekeeping forces and is thus better executed by more heavily armed forces.

Historical Evolution: 

The United Nations is the leading peacekeeping body but there is no explicit UN Charter basis for peacekeeping. UN peacekeeping emerged during the Cold War as a pragmatic, ad hoc response to conflicts between states where the warring parties were willing to accept the deployment of a neutral third party to help keep the peace and to prevent the resumption of fighting while diplomacy could be pursued to resolve the conflict. The first UN peacekeeping operation, the UN Truce Supervision Organization (UNTSO), was launched in 1948 to monitor the ceasefire agreement between Israel and its Arab neighbors in the wake of the Israeli war of independence that same year. Because UNTSO, which remains an active operation, involved unarmed military observers, some choose instead to date the first UN peacekeeping operation from 1956, when, in order to facilitate the disengagement of British, French, and Israeli troops from Egypt following the Suez Crisis, the Canadian diplomat Lester Pearson suggested the stationing of a multilateral armed force—what became known as the UN Emergency Force (UNEF)—to help keep the peace until a political settlement could be reached.

From 1948 until 1988, 13 UN peacekeeping operations were established. For their “decisive contribution” to the resolution of conflict around the globe, UN peacekeeping forces were awarded the Nobel Peace Prize in 1988. Peacekeeping was institutionalized within the United Nations with the establishment of the Department of Peacekeeping Operations (DPKO) in 1992 (although the UN General Assembly had established the Special Committee on Peacekeeping Operations back in 1965). The thawing and then the end of the Cold War saw a dramatic surge in the number of UN peacekeeping operations: from 1988 until 2010, the UN launched 50 new operations. The growth in the number of peacekeeping operations was accompanied by an expansion in the mandated tasks that UN peacekeepers were expected to perform. From observing, monitoring, and supervising ceasefires, peacekeeping operations now might be required additionally to support the delivery of humanitarian aid; protect civilian populations; assist with the disarmament, demobilization, and reintegration of former armed combatants; supervise and assist with the organization of elections; assist in the restructuring and reform of armed forces and police; promote respect for human rights and investigate alleged human rights violations; help to facilitate the repatriation and resettlement of refugees and internally displaced persons; and strengthen the rule of law, including assistance with judicial reform; among other tasks. These expanded operations are often referred to as complex, multi-dimensional, or multi-functional peacekeeping to distinguish them from traditional peacekeeping. In a few exceptional cases (e.g., UNMIK in Kosovo and UNTAET in East Timor), the United Nations has even served as the de facto governing authority of a state or territory. There has also been a limited proactive use of UN peacekeeping forces for the purpose of preventing the eruption of armed conflict (e.g., UNPREDEP in Macedonia).

While UN peacekeeping forces have often executed many of these new tasks well, others have been more problematic. UN peacekeeping forces have sometimes been expected to carry out these tasks in hostile environments where the consent of the warring parties has not always been assured. In such cases peacekeeping has often required actions more in line with peace enforcement, and the success of these operations has been very variable as a consequence. In the former Yugoslavia and Rwanda in the mid-1990s, the limitations of UN peacekeeping were especially evident and the perceived failure of the United Nations in these cases resulted in the attenuation of international support for UN peacekeeping. These difficulties had been anticipated by UN Secretary-General Boutros Boutros-Ghali, who in 1992 called for the establishment of “peace-enforcement units” to deal with challenges that exceed peacekeeping, but such units have never been created. National and multinational forces, such as those of the North Atlantic Treaty Organization (NATO), have sometimes been called upon instead to assist UN peacekeeping operations with enforcement.

Despite these difficulties, support for UN peacekeeping grew again in the late 1990s. By 2010, with nearly 100,000 uniformed personnel in the field (up from 14,000 in 1998), the United Nations was second only to the United States in the number of deployed armed forces under its command. The surge in global peacekeeping activity has not been limited to the United Nations, however. The number of peacekeeping operations undertaken by regional organizations doubled between 1995 and 2005. The African Union (AU), the Economic Community of West African States (ECOWAS), the European Union (EU), NATO, and the Commonwealth of Independent States (CIS) all launched major peacekeeping operations of their own in that period, not only in response to increased demands on the United Nations but also out of an interest by these organizations to strengthen their capacity for the management of security challenges in their regions and, in some cases, farther afield (e.g., EU in Chad and Aceh, NATO in Afghanistan).

Theoretical Implications: 

There is no formal doctrine of UN peacekeeping. Rather, principles of peacekeeping have emerged from reflections on practice. The UN’s “Capstone Doctrine” (2008), while not an official document, represents an attempt to codify these principles. The fundamental principles of UN peacekeeping are consent, impartiality, and the minimum use of force. Consent of the belligerents helps to ensure that the United Nations will have the cooperation of the warring parties, without which it is difficult if not impossible to keep the peace as peacekeeping forces are not usually equipped to enforce a peace. Consent can be withdrawn, however, or may not obtain at all levels of authority (political, strategic, and tactical), especially where irregular forces are involved, which makes its maintenance uncertain. Impartiality means that the peacekeeping mandate must be applied without favor or prejudice to any party. This does not mean that peacekeepers must be neutral or even-handed in their treatment of belligerents; rather, peacekeepers must adhere strictly to the terms of their mandate and not take sides in a conflict. This distinction may be lost on the belligerents themselves, however, who may interpret the peacekeepers’ redress of violations as partiality. Non-use of force (except in self-defense and in defense of the mandate) reflects the fact that peacekeepers are acting with the consent of the parties to the conflict and thus should not be required to employ force to carry out their functions. If force is used it is expected to be calibrated and precise and in conformity with international humanitarian law.

As the demands placed on peacekeeping operations have changed over the years, the principles that underpin them have been subject to shifting emphases and interpretations. In the early 1990s, when the increased incidence of ethno-nationalist civil wars gave rise to grave violations of humanitarian law, pressures on the United Nations to act to prevent or mitigate these crimes resulted in a downgrading of consent as a requirement for UN peacekeeping. In his Agenda for Peace (1992), Boutros-Ghali famously defined peacekeeping as the deployment of a United Nations presence in the field, “hitherto with the consent of all the parties concerned…” (emphasis added). However, the inability of UN peacekeeping forces subsequently to fulfill their mandate, most notably in Somalia, Bosnia-Herzegovina, and Rwanda, led to renewed appreciation of the importance of consent but also of the need for UN peacekeepers to be better equipped to use force in the face of would-be spoilers. Similarly, the humiliation that the United Nations suffered for failing to prevent genocide in Bosnia-Herzegovina and Rwanda led subsequently to recommendations that the organization not allow concerns about impartiality to prevent discrimination between aggressors and victims in the field. The meaning of the “minimum use of force,” too, has undergone expansion to include defense of the mandate and not just of the peacekeepers. Such flexibility is necessary when dealing with dynamic and varied conflict environments but it has also led to confusion as to how these principles should be applied and a blurring of the lines between peacekeeping and peace enforcement. There is also some debate as to other, additional principles that should perhaps guide peacekeeping. The Australian Defence Force, for instance, adds to the core three principles another eight: legitimacy, respect for sovereignty, credible force structure and composition, mutual respect, transparency, unity of command, interoperability, and freedom of movement.

The expansion of peacekeeping practice, and the debate it has spurred, has been one of the most significant developments in peacekeeping since the inception of the institution. While this expansion has created enormous burdens for the United Nations, arguably it has also made the Organization a more indispensable actor in the maintenance of international peace and security.

Practical Applications: 

Debates surrounding the expansion of peacekeeping activities prompted the UN DPKO to initiate a process in 2006 that led, in 2008, to the production of a “Capstone Doctrine” for peacekeeping operations. In the absence of a formal peacekeeping doctrine, the document provides an articulation of the guiding principles of UN peacekeeping that are to be used to inform the work of planners, practitioners, and trainers. The “doctrine” is derived from an analysis of the key Security Council and General Assembly resolutions; the Organization’s internal rules, policies, and guidelines; the findings of relevant high-level panels; and evolving practice. Similar initiatives have been undertaken in recent years by regional security organizations, including NATO and the African Union.

The growing importance of regional organizations for peacekeeping and peace enforcement in the post-Cold War era is another notable trend. The deployment of regional forces has either been at the request of the United Nations and in support of UN peacekeeping or it has represented unilateral initiatives. Regional forces can be a useful complement to UN peacekeeping, especially since the United Nations is unable or unwilling to deploy peacekeeping forces everywhere that the need arises, and indeed the Charter foresees a role for regional arrangements in peace maintenance (Ch. VIII). However, regional organizations, and the individual states within them, will often have their own views and practices of peacekeeping that may reflect more parochial considerations. In some cases, for instance, regional organizations engaged in peacekeeping have been accused of pursuing their own strategic interests first and foremost. Even where national forces serve in UN peacekeeping operations, problems arise when commanders of these forces in the field are more responsive to their national capitals than to the United Nations.

Another matter of concern is the global division of labor that has come to characterize UN peacekeeping in recent years. Historically, developed countries have been important troop-contributing nations to peacekeeping operations. These powers have become increasingly averse to the risks of peacekeeping, however, and as a result developing countries now provide the large majority of UN peacekeepers (troops and police). While it is true that the greatest need for peacekeeping is often in developing countries, it is also true that developing countries are often less well equipped to respond to these needs. The strengthening of regional peacekeeping capacity is one approach that is favored but increased burden-sharing may also be required if peacekeeping is to deal effectively with some of the difficult problems it is asked to tackle.

References / Further Reading: 

Alex J. Bellamy, Paul D. Williams, and Stuart Griffith, Understanding Peacekeeping, 2nd edn (Cambridge: Polity Press, 2010)

Boutros Boutros-Ghali, An Agenda for Peace: Preventive Diplomacy, Peacemaking and Peace-Keeping (New York: United Nations, 1992)

Challenges Project, Meeting the Challenges of Peace Operations (Stockholm: 2005), available at

William J. Durch with Madeline L. England, ‘The Purposes of Peace Operations,’ in Annual Review of Global Peace Operations 2009 (Boulder, CO: Lynne Rienner, 2009)

Trevor Findlay, The Use of Force in UN Peace Operations (Oxford: Oxford University Press, 2002)

Alan James, Peacekeeping in International Politics (New York: St Martin’s, 1990)

Bruce Jones, ‘Evolving Models of Peacekeeping: Policy Implications & Responses’ (New York: Center on International Cooperation, 2004)

Peter Londey, Other People’s Wars: A History of Australian Peacekeeping (New South Wales: Allen and Unwin, 2004)

North Atlantic Treaty Organization, Peace Support Operations, AJP 3.4.1 (Brussels, 2002)

Michael Pugh and Waheguru Pal Singh Sidhu, The United Nations and Regional Security: Europe and Beyond (Boulder, CO: Lynne Rienner, 2003)

Oliver Ramsbotham and Tom Woodhouse, Encyclopedia of International Peacekeeping Operations (Oxford/Denver: ABC-CLIO, 1999)

Steven R. Ratner, The New UN Peacekeeping: Building Peace in Lands of Conflict after the Cold War (New York: St Martin’s Press, 1994)

UK Ministry of Defence, The Military Contribution to Peace Support Operations, 2nd edn., JWP 3-50 (Shrivenham: The Joint Doctrine & Concepts Centre, June 2004)

United Nations, Report of the Panel on UN Peace Operations [‘the Brahimi Report’], UN Doc. A/55/305-S.2000/809, 21 August 2000

United Nations, Department of Peacekeeping Operations and Department of Field Operations, United Nations Peacekeeping Operations: Principles and Practice [‘Capstone Doctrine’] (New York, 2008)

United Nations Department of Peacekeeping Operations official website:

US Army, Stability Operations, FM 3-07 (Washington, DC: Headquarters of the Army, October 2008)