On 29 May 1948, the Security Council, in resolution 50 (1948), called for a cessation of hostilities in Palestine and decided that the truce should be supervised by the UN Mediator, with the assistance of a group of military observers. The first group of military observers, which became known as the United Nations Truce Supervision Organization (UNTSO), was the  first   peacekeeping mission established by the United Nations. UNTSO Military Observers remain in the Middle East to monitor ceasefires, supervise armistice agreements, prevent isolated incidents from escalating and assist other United Nations peacekeeping operations in the region.