No one has mentioned this yet, so I'll give it a shot:
Non-proliferation is a pipe-dream. Just like gun control. Free market says if someone wants a nuke bad enough (demand) someone will sell them one (supply).
Sure there are only so many breeders in the world, and all the international controls, IAEA and all that, but come on, we just found out that the North Koreans were developing weapons. Sooner or later, everyone's going to have the bomb, especially considering the rate at which the "third world" is advancing technologically. Every research university established in [wherever] puts that particular contry one step closer to producing one.
And that's OK. It better be, because there's not a thing we can do to stop it. I fully expect to see a nuclear incident occur in the continental US in my lifetime, but I'm not upset about it. No one in my family lives anywhere near a likely target, so we'll be alright. And like a few other folks said, it will alter the voting base in this country permanently, maybe even for the better. Who nows? At least something will happen to knock us out of this rut. Maybe the pollitical landscape will swing back around to an emphasis on personal freedom when everyone realizes that no government, no matter how powerful and benevolent, can keep you safe. I wouldn't bet on it, though. But even a big sudden push toward total government control of everything might have a silver lining. Maybe people in this country would wake up, and take control of thier government back.
Back on topic: How the American mob expects the government to deal with a nuclear attack would depend on timing more than anything, I think. "Can we prove who it was?" being the number one question. If we could, whether or not the government let that bit of info get out or not would say a lot about what kind of public reaction the government wanted. Maybe that's being paranoid, but it's not like any of us could verify the story the media fed us.