Why were the United States and the Soviet Union suspicious of each other after World War II, and what events that took place between 1945 and 1949 heightened the tensions between the two nations?

Why were the United States and the Soviet Union suspicious of each other after World War II, and what events that took place between 1945 and 1949 heightened the tensions between the two nations?

Book for course is Contemporary World History
William J. Duiker, 2021
Cengage