In response to a request from Count Folke Bernadotte, the Swedish United Nations Mediator for Palestine, and the Secretary-General of the United Nations, Trygve Lie, sent 50 members of the United Nations guard force from Lake Success to assist the Mediator in supervising the Truce in the former British Mandate of Palestine in 1948, the first peacekeeping operation was established by the United Nations. All the members of the party were experienced international civil servants with a background of service with the United Nations Secretariat at Headquarters. While on duty in Palestine, they were to continue to wear United Nations guard uniforms. United Nations military observers (UNMOs) remain in the Middle East to monitor ceasefires, supervise armistice agreements, prevent isolated incidents from escalating and assist other UN peacekeeping operations in the region. This resolution formed the basis for the establishment of the first UN peacekeeping operation which became known as the United Nations Truce Supervision Organization (UNTSO).