The Truman Doctrine was an American foreign policy whose stated purpose was to counter Soviet geopolitical expansion during the Cold War. One of Turkey's most important international relationships has been with the United States since the end of the Second World War and the beginning of the Cold War. Turkey's began to associate with the United States in 1947 when the United States Congress designated Turkey, under the provisions of the "Truman Doctrine", as the recipient of special economic and military assistance intended to help it resist threats from the Soviet Union. In support of the US' overall Cold War strategy, Turkey contributed personnel to the United Nations forces in the Korean War (1950–53) and joined NATO in 1952. A mutual interest in containing Soviet expansion provided the foundation of US–Turkish relations for the next four decades.