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The data and research currently presented here is a preliminary collection or relevant material. We will further develop our work on this topic in the future (to cover it in the same detail as for example our entry on World Population Growth).

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The United Nations was founded after the Second World War with the guiding principle to promote international cooperation and prevent future conflicts. Today, the UN continues to promote peace and has active peacekeeping operations around the world. In addition to peacekeeping, “peacekeepers are increasingly charged with assisting in political processes; reforming judicial systems; training law enforcement and police forces; disarming and reintegrating former combatants; supporting the return of internally displaced persons and refugees.”1

International Peacekeeping Operations

Since the UN does not have its own military it relies on contributions from member states. The role of these peacekeeping forces is not to engage in combat but to prevent future conflict and support stabilization and rebuilding efforts. The mandate of the early peacekeeping operations “was primarily limited to maintaining ceasefires and stabilizing situations on the ground, providing crucial support for political efforts to resolve conflict by peaceful means.”2

Modern peacekeeping forces include economists, police officers, legal experts, electoral observers, human rights monitors as well as military personnel.

The first two peacekeeping operations are still ongoing; these are the United Nations Truce Supervision Organisation (UNTSO) in the Middle East and the United Nations Military Observer Group in India and Pakistan (UNMOGIP). The first armed peacekeeping operation was the First UN Emergency Force (UNEF I) in response to the 1956 Suez Crisis in Egypt. At the end of the Cold-War the focus of UN peacekeeping shifted from primarily dealing with inter-state conflicts to intra-state conflicts/civil wars. For more information on conflict see our entry on War and Peace.

Not all peace keeping missions are conducted by the UN. The bar chart shows the breakdown of peacekeeping operations by organisation for the decade 2004-2013. In many cases, it is regional alliances or organisations that step in to stabilise conflict zones.

Number of united nations peacekeeping operations around the world 1948 2014 v3 850x600
Click to open interactive version
Number of peace operations by conducting organizations, 2004-2013 – SIPRI3
SIPRI Number of multilateral peace operations by organisation

Peacekeeping Personnel

Throughout the Cold War, the change in the number of UN peacekeepers roughly corresponds to changes in the number of active operations globally. With the collapse of the Soviet Union and the end of the Cold War, this relationship breaks down. We see large dip in UN personnel size in the late 90s but only a smaller reductions in the number of ongoing operations. A large part of this decline in personnel numbers can be attributed to the failure of the United Nations Operation in Somalia II (UNOSOM II) and the UN’s withdrawal from Somalia in 1995. The UN’s Peacekeeping website explains:

Missions were established in situations where the guns had not yet fallen silent, in areas such as the former Yugoslavia – UN Protection Force (UNPROFOR), Rwanda – UN Assistance Mission for Rwanda (UNAMIR) and Somalia – UN Operation in Somalia II (UNOSOM II), where there was no peace to keep.

These three high-profile peacekeeping operations came under criticism as peacekeepers faced situations where warring parties failed to adhere to peace agreements, or where the peacekeepers themselves were not provided adequate resources or political support. As civilian casualties rose and hostilities continued, the reputation of UN Peacekeeping suffered.

The setbacks of the early and mid-1990s led the Security Council to limit the number of new peacekeeping missions and begin a process of self-reflection to prevent such failures from happening again.

Successes and failures of peacekeeping

In this section


In recent years, the peacekeeping operation of the UN in Sierra Leone has become an often cited example of successful peacekeeping. From 1999 to 2005, UN peacekeepers worked in Sierra Leone to stabilise the country during and after the civil war. The main objectives of the mission were to assist in the disarmament and enforce the terms of the Lome Peace Agreement. The UN was also involved in setting up a court to try those accused of crimes against humanity, war crimes and violations of both international humanitarian law and domestic laws.

A study by Virginia Page Fortna titled Does Peacekeeping Work? looked directly at the outcomes of peacekeeping in instances of civil war.4

She finds that while on average peacekeeping missions have a lower success rate (defined as continued peace), this is due to a selection effect. The selection effect exists because the decision to intervene is not random — neither is the onset of conflict. Peacekeeping missions are less successful on average because the UN and other peacekeeping organisations only intervene in the most challenging and difficult conflicts. Controlling for these factors, she finds that the presence of peacekeepers reduces the risk of sliding back into civil war by 80 percent. More information on civil wars can be found on the Civil War, Our World in Data page.


Unfortunately, the successes of recent UN peacekeeping operations are overshadowed by its failures in Europe and Africa. The Srebrenica Massacre during the Bosnian War of 1992-95 happened on the watch of Dutch UN peacekeepers. The massacre of 8,000 muslim men and boys is the worst massacre to have taken place in Europe since the end of the Second World War.

In Africa, the UN failed to prevent the Rwandan genocide of 1994 which left between 500,000 and 1,000,000 people dead. In addition to this, UN peacekeepers in Somalia were forced to withdraw after the situation deteriorated in 1995. The Somali Civil War continued after the UN withdrawal and is still ongoing. Most recently, reports have emerged of UN peacekeepers sexually abusing children in the Central African Republic. The current UN secretary general, Ban Ki-moon described the problem as a “cancer in our system” and has vowed to tackle the problem.5

Data Quality & Definitions

All data on UN peacekeeping operations comes from the UN itself and is available online at https://peacekeeping.un.org/en/.

Data Sources

Stockholm International Peace Research Institute (SIPRI)

  • Data: SIPRI Multilateral Peace Operations Database; “The SIPRI database on multilateral peace operations provides comprehensive, reliable and authoritative data on all multilateral peace operations (both UN and non-UN) conducted around the world”
  • Geographical coverage: Global by country or peacekeeping operation
  • Time span: 1948-2014
  • Available at: http://www.sipri.org/databases/pko

United Nations

  • Data: Monthly reports on peacekeeping operations
  • Geographical coverage: Global by country or peacekeeping operation
  • Time span: 1948-2014
  • Available at: https://peacekeeping.un.org/en/

Global Policy Forum

Providing for Peacekeeping

  • Data: IPI Peacekeeping Database: “Drawing from archival UN records, the International Peace Institute Peacekeeping Database presents the first publicly available database of total uniformed personnel contributions of each contributing country by month, by type (troop, police, or expert/observer) and by mission, from November 1990 to present.”
  • Geographical coverage: Global by country or peacekeeping operation
  • Time span: 1947-2012
  • Available at: http://www.providingforpeacekeeping.org