After World War II, many people were scared that a World War III might start, probably between the United States and the countries of Europe, on one side, and the Soviet Union, and maybe China, on the other side. After World War II, countries had many powerful weapons, including jet bomber airplanes that could carry many powerful bombs fast and far, nuclear weapons (or atomic bombs) which could destroy many buildings and kill many people instantly, and missiles which could carry nuclear weapons to other countries very fast. 