As a result of the concept of nuclear deterrence during the Cold War, both the United States and the Soviet Union were unwilling to build dangerous, destructive weapons, which would have encouraged war.
both the United States and the Soviet Union were willing to build weapons that were increasingly dangerous to stop the other side from attacking.
both the United States and the Soviet Union signed treaties to deter the development and testing of nuclear weapons.
both the United States and the Soviet Union agreed to work together to develop and test nuclear weapons to prevent future wars.

B. both the United States and the Soviet Union were willing to build weapons that were increasingly dangerous to stop the other side from attacking.