In the event of a nuclear war, both sides will be so badly harmed that it will be impossible to declare one side or the other as the winner, even if one of them tries to attack and disable the nuclear weapon of its rival, the other would still be left with enough nuclear weapons to inflict unacceptable destruction. Both sides have the capacity to retaliate against an attack and to cause so much destruction that neither can afford to initiate war. This, the cold war-inspite of being an intense form of rivalry between great powers-remained a 'cold' and not hot or shooting war. The deterrence relationship prevents war but not the rivalry between powers.
Why can't nuclear war between the two nuclear powers be decisive?

Explanation

(ii) It could never be decisive as each power had ample stock of nuclear weapons. Even after getting destroyed they could cause destruction and then no body would be victories.