Interesting, and I've said all along that the US and China should not, and in my opinion will not, "go to the mattresses" over the DPRK. That would certainly not be in China's best interests, and a war with the DPRK would ruin the economy of the ROK, the fourth largest economic power in Asia.

But I suggest reading this, long though it is. You might also want to browse through the materials
here, and poke around in here.

I have gone into this in some depth because I was there when I was in the Army (1969) and now have a far, far better understanding of what went on and what is going on now than I ever did then. From the point of view of an old Infantryman, I'd much rather folks talked and resolved things peaceably.