Well, Americans are scared of Communism because they see how the citizens felt while under it's influence (scared and oppressed) and how greedy the central government was, and they saw the citizens being tortured because they didn't like the ruler, or they did something completely harmless, but the government didn't like it.
communism
They feared the spread of Communism
The fear of communism influencing Americans.
Americans showed the fear of communism thorough the McCarthy trials. The trials tried many innocent people for fear they supported communism. Students practiced duck and cover drills in case of raids.
Communism
Communism
American's feared communism for how it could change their lifestyles and Lenin had the ability to bring communism to America with Russia's army.
Americans were very worried about the threat of Communism in the 1950s. This fear was so prevalent at the time that the 1950s are often called the time of the "Red Scare."
In the 1940s and 1950s, Americans had a cultural hysteria about the Soviet threat.
Hm. That is a generalization. 'Americans fear the grow of foreign power' is a fallacy. Americans have feared Communism and the threat of terror but not foreign influence or power. But theoretical, if we were to take your question seriously than Americans could fear the loss of their unipolar power staus in the international community as it is being transformed into a multipolar community.
they feared that if communism spread it would continue to spread and possibly start another world war
Most Americans knew and know nothing about Communism, the movement for a classless stateless society based on production for use.