At the conclusion of the cold war there enough nuclear weapons existed to create this level of destruction:

The correct answer is Mutually assured destruction.

This term was used throughout the Cold War era. Mutually assured destruction means that if nuclear warfare were to ever occur, both countries would be completely destroyed due to the amount of military technology each country had. The US and Soviet Union came close to this type of destruction multiple times during the Cold War, but were able to negotiate deals before it ever actually happened.