Question

What factors led the wartime alliance between the United States and the Soviet Union to disintegrate into the Cold War?

Answer 1

The Soviet Union's growing power and influence was seen as a threat to the USA's national security, which led to the Cold War.

Answer 2

Just adding to alli14344's answer -- there was also increased suspicion on both sides, especially by the USSR under Stalin. The USSR under him had also aggressively pursued its communist agenda in Eastern Europe (they had backtracked on providing democratic elections and when they were held, communist candidates were often the "winners").

Answer 3

Thank you both so much! :)