[2] The Korean Peninsula had been divided along the 38th parallel north since the end of World War II between the occupation forces of the United States and the Soviet Union.

Each sought to prop up a government on its side of the border, and as the Cold War began to take shape, tensions rose as a proxy conflict developed in Korea.

At the end of World War II, the Korean Peninsula, which up to that point had been occupied by the Empire of Japan, was divided along the 38th parallel north.

[3] The Soviet Union (USSR) had moved forces into the northern half of the country, overseeing its establishment as the communist Democratic People's Republic of Korea (DPRK) under Kim Il Sung, a figure who had previously risen to notability for his successes fighting the Japanese.

[4] American forces occupied the south, overseeing the establishment of the Republic of Korea under Syngman Rhee, an ardently anti-communist autocrat.

After observing elections in South Korea, the General Assembly stated on 12 December 1948 in their Resolution 195, that the nation was to be established under one government as soon as possible, and the US and Soviet occupation forces there were to withdraw.

On the night of 25 June 1950, ten divisions of the North Korean People's Army launched a full-scale invasion of the Republic of Korea.

[13] As the combat grew more intense, US Secretary of State Dean Acheson informed President Truman, who had been resting at his Missouri home over the weekend), and Trygve Lie, the Secretary-General of the UN, of the situation.

Fearing the attack would spur another general war between great powers, Truman resolved to act as quickly as possible to prevent an escalation of the conflict.

[9] Muccio met with Rhee, who informed him the South Korean Army would run out of ammunition within ten days, and would not be able to hold back the invasion on its own.

Myon read a prepared statement calling the invasion a crime against humanity, and said that as the UN had played a major role in the founding of South Korea, it was their responsibility to help defend it from aggression.

[20] Earlier in the day, independent of the UN resolution, Truman had ordered the Joint Chiefs of Staff to contact General of the Army Douglas MacArthur, who was in charge of US forces in the Far East.

He ordered MacArthur to prepare ships for the evacuation of US citizens from Korea, and authorized him to send ammunition and supplies to Pusan to support South Korean forces in the Seoul–Kimpo area.

[20] Within days, ships and aircraft from several nations, as well as the first major formations of US troops, were moving to South Korea, setting the stage for a full-scale conflict.