They don’t need nukes. All of North Korea’s assets are pointing south. If NK moves them north, China will see that as a threat to them. If China comes over the border, it will be a short fight.
Kim’s in a bind. The bigger question is what Kim will do with his nukes. Maybe that is why the ships are there, protecting Japan with the SM-3’s which can shoot down ballistic missiles.
All I want is a full-on nuclear war.