Kenneth Waltz has argued nuclear weapons spread peace. The strongest evidence supporting him is the lack of any nuclear conflict in the last sixty years and the way the weapons have brought peace between India and Pakistan. If he is right the best prospects for long-term peace in the middle east will probably come through a nuclear-armed Iran.

http://en.wikipedia.org/wiki/Kenneth_Waltz

That said, there are two core ironies in the politics of proliferation that make this suggestion uncomfortable. The first is that at least at present the most vehement opponents of nuclear proliferation are often the most vocal critics of gun control. So few people who talk about the importance (or insignificance) of deterrence really seem to believe it logically.

The second irony is that the Nash equilibrium for rational-actor based models of deterrence is not peace, but random violence. The reason for this is that a certain amount of "demonstrated irrationality" is required to make the prospect of mutual assured destruction convincing to all players. Which means that if the world were truly rational we would expect some use of nuclear devices. And yet we don't see any, or haven't seen any yet.

All of which leads us to the strange observation that nuclear proliferation seems to bring peace, but not because of a rational deterrent effect.