America's fear of communism from 1947-1953 was due to the increased political power of the Soviet Union. The Soviet Union had a communist system in which Stalin abused his power and took away civil liberties from his citizens. After World War II, his power continued to increase as the Soviet Union was allied/had control over several different countries in Europe including Romania, Bulgaria, Albania, and Czechoslovakia. America was worried that this communist influence would continue to spread all over the world.
The fear of communism was not only present overseas, but also in America. During World War II there were Soviet spies in the US that gave information to the Soviet government. This, along with a small communist party in America, allowed for the development of McCarthyism. McCarthyism was essentially a witch hunt for any suspected communists. Anyone perceived as a communist threat could be called in front of Congress in the House Un-American Activities Committee (HUAC).
