Events that led to the beginning of the Cold War. (DBQ)?

Question

1941-1949 Events that led to the increaded tension/suspicion between the US and Soviet Union... (Marshall Plan)

Answer 1

Nuclear weapon development by US and subsequent development by USSR. Refusal by Stalin to honor Yalta agreement and allow elections in Eastern European nations. Marshall Plan funding offered to Eastern European nations but not allowed by USSR. Increased tensions in split Germany and especially over Berlin.