The main objective of the Truman Doctrine during the Cold War was to contain the spread of communism. Announced in 1947, President Harry Truman articulated the U.S. responsibility to support free peoples resisting subjugation by armed minorities or outside pressures, primarily aimed at countering Soviet influence. The doctrine marked a significant shift in U.S. foreign policy, transitioning from isolationism to active involvement in global affairs. It initiated a commitment to provide political, military, and economic assistance to nations threatened by communism, signifying the start of a broader strategy of containment that would define U.S. engagement during the Cold War era.