what did the truman doctrine declare
From Wikipedia, the free encyclopedia. The Truman Doctrine was an American foreign policy to stop Soviet imperialism during the Cold War. It was announced to Congress by President Harry S. Truman on March 12, 1947 when he pledged to contain Soviet threats to Greece and Turkey.No American military force was involved; instead Congress appropriated a free gift of financial aid to support the economies and the militaries of Greece and Turkey.he Truman Doctrine became the foundation of American foreign policy, and led in 1949 to the formation of NATO, a full-fledged military alliance that is in effect to this day.