This forced the United Nations to retreat and the U.S became involved in an extensive land war in Asia. In this war, Truman had ruled out the use of both atomic weapons and large numbers of troops. This led to a very frustrating 2.5 year stalemate that ended in a draw. Eventually, the Chinese were able to push U.S. and Korean troops out of North Korea completely and speculation of nuclear war with Soviet Union became a heavy topic.
Korean Armistice Agreement (1953).
On July 27, 1953, the U.S, North Korea, South Korea, and the People's Republic of China agreed to an armistice, which brought the Korean War to an end. With the agreement, a distinct border between North and South Korea was established. South Korea gained some extra territory and a demilitarized zone between North and South was established. The details in the Korean Armistice Agreement included: all open hostilities were to be ended, there were to be zero military equipment and forces within a 4000 meter wide zone on either side of the border, both sides are prohibited from entering the air, ground, or sea areas under control of the other, all prisoners of war and displaced persons were to be released, and established the Military Armistice Committee (MAC) to make sure the countries involved followed the rules set in place.
U.S Involvement.
The United States spent a total of 30 billion U.S dollars of the Korean War (equivalent to $341 billion in 2011). The U.S sent 5,720,000 troops to aid South Korea in the war. Out of that number, 36,000 U.S troops were killed and 105,000 were wounded. After the war, American forces stayed in South Korea to help rebuild the nation for a short period of time. Outside of the war and supporting the South Korean side with troops and supplies, the U.S involved themselves in South Korean politics. South Korea and the U.S worked together from 1945-1989 because they were both diplomatic states and shared similar interests.