What was the main reason that the United States adopted policies to stop the spread of communism around the world?

They wanted to stop the Soviet Union from gaining power.

Explanation:

After World War II, the US and Soviet Union emerged as global superpowers. The US wanted to spread capitalism and democracy while the Soviet Union wanted to spread communism. The US disliked the communist system because it limits the individual freedoms of citizens. This is due to the fact that the government controls businesses, media, etc.

The United States did not want communism to reach their shores