Final answer:
The Truman Doctrine and the Marshall Plan were central to the U.S. containment policy during the Cold War, with the former focusing on political and military support to resist Communism and the latter on economic recovery aimed at thwarting Communist influence in Europe.
Step-by-step explanation:
The Truman Doctrine and the Marshall Plan were instrumental to the American strategy of containment, which was the policy aimed at preventing the spread of Communism beyond its borders post-World War II. The Truman Doctrine articulated a policy of U.S. intervention against the spread of Communism, explicitly supporting free nations against subjugation by Communist minorities. The doctrine turned into action when the U.S. provided military and economic assistance to Greece and Turkey, supporting them against Communist forces. On the other hand, the Marshall Plan aimed at the economic recovery of war-torn European nations, offering considerable aid to strengthen these countries against the threat of Communist expansion.
These strategies shared a common goal of containment but differed in execution; the Truman Doctrine was principally a military and political stance against Communist expansion, while the Marshall Plan took an economic approach, fostering rebuilding and growth to create prosperous, and consequently stable, societies less susceptible to Communist ideologies. The effectiveness of these policies was a matter of great importance, shaping the Cold War dynamics and leading to the establishment of NATO to secure mutual defense against Communist expansion, and indirectly, prompting the formation of the Warsaw Pact by the Soviet Union and its allies.