You can carpet bomb them all you want. You'll eventually need someone sane in power to surrender the nation to you.
I didn't mention carpet bombing or surrendering. You're creating scenarios outside of what is being mentioned. Admittedly, my solution is a fantasy (due to politics), but is very feasible.
North Korea doesn't have much to fight with. Considering everything to be functional and/or done in accordance with procedures, their missiles will never do any real damage. That is their only hope. Their Army wont make it far past the DMZ. They don't have the computer power to do any cyber attacks, so they're powerless. At that point, NK will concede as opposed to surrendering, which would be a win for everyone else. No carpet bombing necessary.
You're falling prey to the media, which is exactly what NK wants. NK is just taunting to draw attention in hopes that someone attacks them first. That way they can spin it. They do this EVERY SINGLE YEAR at the SAME TIME. The only attack NK will do will be like the sinking of the ship. Something that is small and able to deny any involvement. Edited, Apr 9th 2013 5:54pm by Almalieque