War is a cruel event that holds no winners, that leaves a trail of death, destruction, and famine in it's wake, and creates widow(er)s, orphans, and so many bodies...
In relation to the Cold War, it was the idea of deterrence through... well, mutually assured destruction. We launch a nuke at them, they launch one at us, our allies launch, their allies launch, and voila, welcome to Fallout.
And since trying to kill one another would inevitably get the attacker reduced to a smoldering crater, it more or less worked. Of course we came damn close to the whole world going kablooey a few times, but still.