Timeline of United States military operations May 1949. 1948–1949: China: Marines were dispatched to Nanking to protect the American Embassy when the city fell to Communist troops, and to Shanghai to aid in the protection and evacuation of Americans. 1950–1953: Korean War: The United States responded to the North Korean invasion of South Korea by going to its assistance, pursuant to United Nations Security Council resolutions. US forces deployed in Korea exceeded 300,000 during the last year of the active conflict (1953). Over 36,600 US military were killed in action. 1950–1955: Formosa (Taiwan): In June 1950, at the beginning of the Korean War, President Truman ordered
South Korea the largest contributor of UN troops. The United States participation was critical for preventing the near defeat of the Republic of Korea by northern forces, as well as fighting back for the territory gains that define the South Korean nation today. Following the Armistice, South Korea and the U.S. agreed to a "Mutual Defense Treaty", under which an attack on either party in the Pacific area would summon a response from both. In 1967, South Korea obliged the mutual defense treaty, by sending a large combat troop contingent to support the United States in the Vietnam War. The US has