Which doctrine was introduced by the United States to counter communism in Europe during the Cold War?

The Truman Doctrine was a significant policy introduced by President Harry S. Truman in 1947, aimed specifically at countering the spread of communism in Europe and beyond. In the context of the emerging Cold War, Truman asserted that the United States had a responsibility to support free peoples who were resisting subjugation by armed minorities or outside pressures, primarily referring to Soviet influence and communism.

This doctrine laid the groundwork for American foreign policy, marking a shift toward a more active role in international affairs with the intent of containing communism. By providing military and economic assistance to nations threatened by communist movements, particularly in Greece and Turkey, the Truman Doctrine highlighted the U.S. commitment to combat communism through direct support and intervention.

In contrast, the Monroe Doctrine primarily focused on opposing European colonialism in the Americas, the Eisenhower Doctrine expanded on Truman's efforts specifically in the Middle East, and the Marshall Plan was primarily an economic initiative aimed at rebuilding European economies after World War II. Thus, the Truman Doctrine is distinctly recognized as the policy that explicitly addressed the challenge of communism in Europe during the Cold War era.