The United Nations Truce Supervision Organization (UNTSO) is an organization founded on 29 May 1948 for peacekeeping in the Middle East. Established amidst the 1948 Arab–Israeli War, its primary task was initially to provide the military command structure to the peacekeeping forces in the Middle East to enable the peacekeepers to observe and maintain the ceasefire, and in assisting the parties to the Armistice Agreements in the supervision of the application and observance of the terms of those Agreements. The organization's structure and role has evolved over time as a result of the various conflicts in the region and at times UNTSO personnel have been used to rapidly deploy to other areas of the Middle East in support of other United Nations operations. The command structure of the UNTSO was maintained to cover the later peacekeeping organisations of the United Nations Disengagement Observer Force (UNDOF) and the United Nations Interim Force in Lebanon (UNIFIL) to which UNTSO continues to provide military observers.

Peacekeeping by the United Nations is a role of the UN's Department of Peace Operations as an "instrument developed by the organization as a way to help countries torn by conflict to create the conditions for lasting peace". It is distinguished from peacebuilding, peacemaking, and peace enforcement although the United Nations does acknowledge that all activities are "mutually reinforcing" and that overlap between them is frequent in practice.