They both did not agree on who should get the title of defating Germany. Berlin was taken over by the USSR straight away as Germany surrendered and both did not want to pay a-lot of money for repairs, also America wanted to help Germany grow and Russia did not
Explanation:
Soviet Union and America was also wrecked by the huge differences between the two countries in: politics - America was capitalist, Russia was communist. lifestyle - America had freedom and a two-party democracy - Russia had secret police and a one-party state.
As the other answers states, the United States and the U.S.S.R. only came together because of the severe threat posed by a common enemy, Nazi Germany. Between 1917 and 1941 relations were tense between the U.S. and the Soviets. After World War II, relations between the U.S. and the U.S.S.R rapidly deteriorated.
