The United States of America became involved in the Korean conflict when the UN had called upon member nations to give military support to South Korea after it had been invaded by the North Korean troops, on the 25th of June, 1950. This invasion was considered to be a violation of international peace, according to the UN. The UN issued an official warning to the North Korean troops to withdraw. However the North Koreans did not withdraw, this resulted with around 40 countries sending military personnel, support and equipment. Close to 90 percent of the UN aid had actually come from the US. However, North Korea also received support- receiving Chinese troops and Soviet military equipment. The Korean war lasted until the 27th of July 1953, when an armistice was called, however a formal peace treaty was never drawn up.