I dont honestly believe though that one man could ever launch a nuclear attack, at least not in the west, without at least first someone very high up advising such a leader to carry out a non conventional as the best course of action.
The same however, cannot be said for such entities as Iran, Iraq and N Korea. As for the Pakistanis and Indians, I am actually not too adverse to them having them, as they again are in the same league as us, purely down to the beaurocratic way both of these coutries run. If anything, posessing nukes might actually have brought a little welcome respect for their neighbour and thus helped the situation..
Flip this around to Iran, and I honestly cannot Say I would trust them to even 30% that they wouldnt go preemtive against Israel, bearing in mind how much support Iran would have in the mideast. I honestly wouldnt even trust these guys with a bb gun, never mind a nuke!!! Alahs will and all that.