the idiots have restarted the war, we would end a 80 year old problem, and it would be a shot across the bow to China...ie win/win/win.
what is there a counter argument?
I think the argument against this type of preemptive strike is overwhelming. What is your argument for using a nuclear strike instead of other options like continued international pressure, cooperation with China, conventional weapons, etc?
If your argument is a preemptive strike prevents N. Korea from launching nucs, I think that fails because if you failed to destroy all of N. Korea's nucs, they would certainly retaliate, even if it was just a backpack nuc in Seoul. Getting the leadership would not be enough. Plus, in an interconnected economy, the ramifications of losing S. Korea and an active cold war between the US and China would devastate the world economy in general and the US economy in particular. Even if there was no negative impact on S. Korea, they would not view the deaths of their fellow Koreans as simply the cost of peace. There is no way the US comes out ahead in world opinion, no way the US economy isn't thrown into a massive tailspin and likely very little benefit. The calculus in N. Korea is pretty clear: sabre rattle all you want, maybe cause a border incident or two, no problems. Bomb anyone and the days of the current regime is limited. Nuc someone and N. Korea will cease to exist within the week with all the world's countries in complete agreement. N. Korea is not going to use a nuc and everyone knows it.
It seems the optimal strategy for the western world is to follow S. Korea's and Japan's lead in diplomacy and let N. Korea continue to piss off the Chinese. If we don't provide some reason for China to strengthen its ties to N. Korea, it will continue to deteriorate and further isolate Pyongyang.