Ideally, we should consider nuclear technology itself the enemy, because 1) there are nuclear weapons that can obliviate us, 2) the presense of nuclear technology mandates us to have our own nuclear weapons to "get" the other country before they "get us".
Nuclear technology is an advancement that's really holding us at gunpoint. It's a philosophical matter. A single paranoid fiasco could obviate half the world...
On the other hand, I suppose the threat of death being closer, the "doomsday clock" being closer to midnight forces world powers to try to act in a more civilized fashion in order to woo each other into you know, not destroying everything, making the world a nicer place.
That's why we take all these preemptive strikes, because the superpowers of the world are trying to be proactive in preventing future war, which would probably use nuclear weapons, creating a horrible, fractured and diseased, sterile world.
The threat of apocalypse could psyche the world into doing anything...it's rather scary, either we all die or we try to initiate an absolute utopia to keep ourselves from dying, and that idea itself could bring the world closer to using our nuclear arsenals. The more actions we take motivated by the threat of nuclear weapons...the more we'll eventually be driven to use them.
Really tests mankind's faith in the Christian doctrine, "turn the other cheek", doesn't it?