With Kim thumbing his nose at us by lobbing ever more capable missiles near the shores of our ally Japan, missiles that if launched on a normal trajectory could now reach U.S. territory, and China dragging its feet, we have no option other than the military one. I know, there's talk of a possible naval blockade of some type, but as that in itself is an act or war and likely to provoke a hostile response, we might as well skip that step and go straight to direct military action.
Personally, I'm not concerned about what the North might do to Seoul in retaliation as they have decided to elect a socialist, refuse our THAAD defensive missile batteries, and instead seem to want to try the "head in the sand approach." I also think that if we apply WWII style "total war" to this problem, using our vastly superior technology, this thing would be wrapped up but for the inevitable diplomatic fallout in a very short timeframe. I just firmly believe that if our military were unleashed unlike it has been allowed because of PC for decades now, North Korea would be decimated before it even knew what was happening.
The Chinese will whisper to Seoul that they will keep NK reined in if SK gets rid of those pesky Americans. Beijing’s end game is to push the US out of the Western Pacific. First SK then Japan will see reason, and kowtow to Beijing. We need to make it clear to Seoul that if they want to point NK at us to spare themselves, then we of course will feel free to defend our own interests no matter what happens to SK.
Conventionally we could hardly dent them. They are dug in and ready. You have to see the in depth fortifications in the North to believe them. Anyone who thinks we could destroy them easily conventionally is, well, wrong.