I think it would be a profound mistake for us to use nuclear weapons in any circumstance...involving civilians. Let me scratch that. There's been no discussion of nuclear weapons. That's not on the table.Desperately wrong answer to (what should be) a deal-breaking question, Mr Obama. Sure, waving the threat of one's nuclear weapons capacity around like a pair of chopsticks in a cheap Chinese restaurant is not sensible, because it ultimately reduces that capacity's deterrent value - which is the only practical reason why a sane nation would field a nuclear arsenal in this world of other nations who also possess The Bomb. A wise leader does not even refer to his country's nuclear weapons capacity, because the widespread knowledge of that capacity speaks for itself more effectively than any politician could ever hope to.
Conversely, it is sheer lunacy for a US President (or hopeful) to declare that he will never press the button, because such statements completely undermine the deterrent value of these weapons. Mr Obama, if you are not running on a platform of nuclear disarmament, you never take the nuclear option off the table. Ever. You made a most elementary strategic blunder - you are not a suitable candidate for the role of U.S. Commander-in-Chief.