Speaking of the devil, where is the UN on all this? Silent as a lamb.Problem is, no matter how fast, the North Koreans would get at least one NUKE off. Where, is anyones guess? I see troops on the ground to pull something that quick and devastating off. All combined forces aworking as one, and it would require a good amount of NATO, if not UN (Smirk) support. Problem is that to drum up that support, NK will have time. Time to prepare. That said, I don't see how, without China's help, North Korea suvives a modern invasion. Yes, they do damage (A lesson for ever allowing Iran to get NUKES), but NK would cease to exist. The damage they inflict on some unsuspecting nation, Japan perhaps, is weighed against the effort to remove the regime, and replace it. Is it worth it? There are a great many people with more information than I that are debating that very subject right now.
Obama, on the other hand, is thnking politically. Politcs will direct his decision, and if it turns out in his mind that politically, it's best to play hardball with more sanctions, then that is what it will be. All the while, making it even more difficult for the next President to resolve.
My guess is that the Norht Korean army would provide stiff resistance at first, but then buckle as their lines of communication get cut. Just like what happened in Iraq.