We did stop for one minute and now that minute has passed. Simple truth is there can be no trust between competing countries. All the major players have proven they can and are willing to do anything for complete hegemony.
They've had time to do the math and see the effects. Once they have countermeasures in place and decide the losses will be worth the price, nuclear war will happen.
Some people are dumb enough to try and make it happen while feeling all smug or righteous about it.
We are that dumb.