Final answer:
The U.S. containment policy during the Cold War sought to prevent the spread of communism beyond Eastern Europe, mainly through economic and military measures.
Step-by-step explanation:
The U.S. policy of containment after World War II was primarily aimed to prevent communism from spreading beyond Eastern Europe. This strategy, mentioned by George F. Kennan in the Long Telegram, emphasized that the Soviet Union's influence had to be confined to its existing borders following World War II. Specifically, it was critical for the United States to keep communism within the nations that were already under the Soviet Union's control. Consequently, various American policies and actions, such as the Marshall Plan and the establishment of NATO, were instituted to halt the spread of Soviet influence.