During the Cold War, what was the main concern of the United States?

1. The Cold War was a long period of tension rather than open fighting. 2. The main concern of the United States during it was Communism. 3. Slavery was a problem that led to the Civil War in the 1800s, a century before the Cold War. 4. Terrorists attacked the United States on September 11, 2001, which came after the Cold War had ended. 5. The cost of the Civil War belongs to the 1800s as well. 6. Placing each option in time is what makes the Cold War answer stand out. _Source: USCIS Civics Flash Cards M-623 (rev. 02/12), public domain, official civics question 83_