Nuclear war is such an emotional subject that many people see the weapons themselves as the common enemy of humanity.

The widespread diffusion of nuclear weapons would make many nations able, and in some cases also create the pressure, to aggravate an on-going crisis, or even touch off a war between two other powers for purposes of their own.

Nuclear weapons are intrinsically neither moral nor immoral, though they are more prone to immoral use than most weapons.

Nothing binds a people to their leader like a common enemy. Voters don't change governments during war.

We need a common enemy to unite us.

From a scientific perspective there is some indication that a nuclear war could deplete the earth's ozone layer or, less likely, could bring on a new Ice Age - but there is no suggestion that either the created order or mankind would be destroyed in the process.