When North Korea invaded South Korea in June 1950, the poor quality of the South Korean armed forces immediately became apparent. Although South Korea had 94,000 troops when North Korea began its all-out surprise attack, one week later only 20,000 troops could be accounted for. By early September 1950, the invading forces held all of South Korea except for the PusanTaegu corridor in the southeast.

The United Nations (UN) Security Council, upon the request of the United States, condemned North Korea's invasion of South Korea and asked members of the UN to assist South Korea. Fifteen nations besides the United States and South Korea eventually provided troops all forces fought under the UN flag and under the unified command of General Douglas A. MacArthur, commander in chief of UN forces. These combined forces successfully broke North Korea's extended supply lines by landing at Inch'on in September 1950. The invading forces were pushed back to near the Chinese border. Only the massive intervention of the Chinese People's Volunteers (CPV) in October averted the defeat of the North Korean forces. United Nations and communist forces fought to a standstill.

In July 1953, an armistice was signed that in 1990 remained the only agreement preventing the renewal of hostilities on the peninsula. The armistice fixed the boundaries of the 241- kilometer Demilitarized Zone as the border between North Korea and South Korea. It also established a Military Armistice Commission, comprising China, North Korea, the United States, and South Korea, to resolve armistice violations and prevent the resumption of hostilities. As of 1990, the Chinese representative still was posted to the Military Armistice Commission, attended its plenary sessions, participated in secretarial meetings, officers of the day meetings, language officers meetings, and observed Neutral Nations Supervisory Commission meetings, but deferred to North Korea's representative.

Data as of June 1990