After the Axis Powers were defeated, the differences between the United States and the Soviet Union came to the front.Having freed Eastern Europe from the Nazis, the Soviet army stayed in the conquered areas and set up pro-Soviet regimes in Poland, Romania, Bulgaria, and Hungary.As Dean Acheson, U.S. undersecretary of state, explained on February 29, 1947:
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# Like apples in a barrel infected by one rotten one, the corruption of Greece would
Infect Iran and all to the east.Truman of the United States, alarmed by British weakness and the possibility of Soviet expansion into the eastern Mediterranean, responded with the Truman Doctrine.