Reading George Monbiot’s suggestion that nuclear proliferation is a self vindicating policy reminded me of the science fiction writings of Phillip K Dick and others. Specifically, stories where the effect precedes its cause, due to some paradox of time-travel or other. Going back in time to kill yourself, or become your own father, or both, that sort of thing.
In the world of global powerplays, the idea of deterrance and pre-emption means that cause can come after the effect – no time-machine or supernova required:

In nuclear politics, every action is justified by the response it provokes … Israel, citing the threat from Iran, insists on retaining its nuclear missiles. Threatened by them (and prompted, among other reasons, by his anti-semitism), the Iranian president says he wants to wipe Israel off the map, and appears to be developing a means of doing so. Israel sees his response as vindicating its nuclear programme. It threatens an air strike, which grants retrospective validity to Ahmadinejad’s designs. And so it goes on. Everyone turns out to be right in the end.

Since, the absence of a time-machine, we cannot return to the beginning of the last century and arrange for nuclear weapons to be uninvented, we fear an escalation. as each side (including the UK) maintains and improves their nuclear arsenal for the next fifty years at least. Negotiating not only non-proliferation, let alone disarmament, seems in itself the stuff of utopian fiction.
Perhaps we should look to another great science fiction story for the answers. In Ender’s Game by Orson Scott Card, the epynonymous hero employs a series of bizarre and often counter-intuitive thinking to win the war games he plays. Perhaps a sudden and unsuspected move could solve the problem. Several people, including a correspndent in Time, suggests that Western nations build Iran enough solar panels to satisfy their energy needs. Alternatively, we could simply disarm unilaterally and without reason, thus confounding the opponent. After all, as Joseph Heller’s Closing Time teaches us, you don’t actually need any weapons to act as a deterrent, you just need to market them properly. Milo’s ‘Ssh’ aircraft can fly silently and bomb targets yesterday (more time-travel, presumably).
Having said that, Joseph Heller’s novels are hardly set in a world of tranquility and sanity, and another of Ender’s teactics is to lauch pre-emptive counter attacks with an all out, willfully destructive force.
Here’s another thought, however: If nuclear arsenals are deterrents, but nevertheless some president does actually lauch a nuclear attack on another country… what exactly would be the point of nuclear retaliation? The destroyed cities would still be beyond repair even after a counter-attack, the only difference being that there would be twice as many of them, and twice as many dead civilians, as after the ‘first-strike’. Humans consider vengenace to be an integral part of justice, but if it means that the aggreate population of the human race is diminished by two million people instead of one million, retaliation seems an inherently useless response.
The best way to prevent a nuclear war would be to ensure that the people who would use the weapons are not in power in the first place. The chain of events that brought Ahmedinejad to power are only now becoming clear. If we wanted a different situation in the Middle-East, we should have acted ten, twenty or thirty years ago. Look’s like we need that time-machine again….