I don't think they have the technical ability to reach the US with a missile at this point. As others have pointed out, they are more likely to either hit on an American ally or maybe aid terrorist groups in getting their bombs.

I have to say that in any unlikely scenario, I hope there is never some automatic retalation that results in any country being "wiped off the map". Countries have civilians in them, men, women and children. What their crazy government does, they do not necessarily support, and a mass death sentence isn't necessarily the answer or the moral thing to do.