How did distrust between the united states and soviet union and the two powers' competing worldviews lead to the cold war?

Though the Soviet Union and the United States were allies during World War II, they became adversaries in the years that followed.  The United States and the Soviet Union were countries with radically different political philosophies.  The Soviet Union was communist and the United States was capitalists.  They were both world super powers.  The United States, up until the early 1950s, possessed the atomic bomb, which greatly worried the Soviets, given that the U.S. had the power to immediately and quickly destroy them.  Once the Soviets had designed their own atomic bombs, the United States was suspicious of the Soviets' goals and power.  Neither side trusted the other not to abuse their power and neither side was willing to disarms themselves.