The United Nations Command (UNC) is the unified command structure for the multinational military forces supporting South Korea (the Republic of Korea or ROK) during and after the Korean War. After troops of North Korea invaded South Korea on June 25, 1950, the United Nations Security Council adopted Resolution 82 calling on North Korea to cease hostilities and withdraw to the 38th parallel.
On June 27, 1950, it adopted Resolution 83, recommending that members of the United Nations provide assistance to the Republic of Korea "to repel the armed attack and to restore international peace and security to the area". Security Council Resolution 84, adopted on July 7, 1950, recommended that members providing military forces and other assistance to South Korea "make such forces and other assistance available to a unified command under the United States of America".
President Syngman Rhee of the Republic of Korea assigned operational command of ROK ground, sea, and air forces to General MacArthur as Commander-in-Chief UN Command (CINCUNC) in a letter (the "Pusan Letter") of July 15, 1950:
In view of the common military effort of the United Nations on behalf of the Republic of Korea, in which all military forces, land, sea and air, of all the United Nations fighting in or near Korea have been placed under your operational command, and in which you have been designated Supreme Commander United Nations Forces, I am happy to assign to you command authority over all land, sea, and air forces of the Republic of Korea during the period of the continuation of the present state of hostilities, such command to be exercised either by you personally or by such military commander or commanders to whom you may delegate the exercise of this authority within Korea or in adjacent seas.
On August 29, 1950, the British Commonwealth's 27th Infantry Brigade arrived at Busan to join the UNC, which until then included only ROK and U.S. forces. The 27th Brigade moved into the Naktong River line west of Daegu.
Troop units from other countries of the UN followed in rapid succession; Australia, Belgian United Nations Command, Canada, Colombia, Ethiopia, France, Greece, Luxembourg, the Netherlands, New Zealand, the Philippines (Philippine Expeditionary Forces to Korea), South Africa (No. 2 Squadron SAAF), Thailand and the Turkish Brigade. Denmark, India, Norway and Sweden provided medical units. Italy provided a hospital, even though it was not a UN member. Iran provided medical assistance from the Iranian military's medical service.
On 1 September 1950 the United Nations Command had a strength of 180,000 in Korea: 92,000 were South Koreans, the balance being Americans and the 1,600-man British 27th Infantry Brigade.
The United Nations Command and the Chinese-North Korean Command signed the Korean Armistice Agreement on 27 July 1953, ending the heavy fighting. The armistice agreement established the Military Armistice Commission (MAC), consisting of representatives of the two signatories, to supervise the implementation of the armistice terms, and the Neutral Nations Supervisory Commission (NNSC) to monitor the armistice's restrictions on the parties' reinforcing or rearming themselves. The North Korean-Chinese MAC has been replaced by Panmunjom representatives under exclusive North Korean management.
Regular meetings have been stopped, although duty officers of the Joint Security Area (commonly known as the Truce Village of Panmunjom) from each side meet regularly.