In the Cold War what was the US worried about?

During the Cold War, the United States was primarily concerned about the spread of communism, particularly the influence of the Soviet Union. The U.S. feared that if one nation fell to communism, neighboring countries would follow, a phenomenon known as the "domino effect." This led to U.S. involvement in various conflicts and support for anti-communist regimes worldwide. Additionally, the arms race and the threat of nuclear war heightened U.S. anxieties about national security and global stability.