How did the Soviet Union actions affect the US?

The soviets responded with its own military buildup, beginning an arms race that would go on for four decades.

Why was the Soviet Union a threat to the United States?
Because USSR was a mass mobilizing totalitarian dictatorship, which occupied most of Eastern Europe, killed and arrested political opposition and even ethnicities seen as a threat to Kremlin, and ran large and influental communist groups/parties in all the western democracies with an ultimate intent to influence…