Final answer:
The United States plan to help Greece and Turkey avoid communism was the Truman Doctrine, where President Truman pledged to support "free peoples" resisting communism.
Step-by-step explanation:
The United States plan to help Greece and Turkey avoid falling to communism was known as the Truman Doctrine. In his address to Congress in March 1947, President Truman pledged to support "free peoples" who were resisting communism. He argued that it was the duty of the United States to oppose "totalitarian regimes." Congress approved his request for $400 million in aid for Greece and Turkey. This doctrine became the basis of U.S. foreign policy throughout the Cold War.