What was the threat that caused so much fear in the Cold War?

There are a few ways to look at this question. One aspect of the Cold War that caused people to be afraid was the fear of nuclear war. Both the United States and the Soviet Union developed nuclear weapons. Each side was making hints that they would use their nuclear weapons. Many people were afraid we would have a nuclear war with the Soviet Union. Some Americans built their own bomb shelters to hopefully protect themselves in the case of a nuclear attack.

Another threat that caused fear during the Cold War was the fear that the communists were going to take over our government. This fear reached hysterical levels in the 1950s when Senator Joseph McCarthy of Wisconsin claimed he knew and had evidence that communists were in all levels of our government. People began to act irrationally, mainly out of fear, and few people were willing to challenge Senator McCarthy because they were afraid they would be accused of being a communist.