Not at the cost of the world economy though, which is the situation we've got. Given that the Norks have -from my recollection- SCUDs and nukes, they can simply load a few and target Tokyo and Seoul and win that way because as either of those facing Openhimer's Light will cause the world economy to go into a tailspin by themselves, both means the Great Depression will look like a picnic. Sure, North Korea would become pot marked with new irradiated lakes in the aftermath, but the damage will already be done and it'll make interesting times for geopolitics.
That is why the US has been investing a lot in ABM tech, particularly ballistic and terminal phase interception. N. Korea has enough cards in its deck to basically ensure that they'll pull a 'from hell's heart, I stab at thee' on the rest of the world... which is why North Korea hasn't been taken out in the last decade when China-N. Korean relations were souring.