Answer:
The superpowers (the United States and the Soviet Union) did not settle their rivalry by decisive military action during the Cold War because they both had nuclear weapons, which made the prospect of a full-scale war between them extremely risky and potentially catastrophic. A nuclear war could have resulted in millions of deaths and the destruction of entire cities. Both sides also had a mutual understanding that a nuclear war would not be in their best interests and that it could potentially lead to the end of civilization.