“If” there are 150,000 Chinese troops on NK border it’s to ensure they can repel the refugees from entering China...
“IF”...
This looks like a co-ordinated move by China-USA and Russia (with Japan and South Korea looking on) North Korea does something—we use tomahawks to take out Nuke Plant & Test Site and the rocket base. (Preemptive Strike—he said he would attack the USA—that’s enough). Chinese invade to “help their ally” Generals shoot the Korean Nut Case. A general selected by North Korea and China takes over and vows to get rid of Nukes and rocket program in exchange for trade with South Korea, and US aid in the form of food. They return the US prisoner and the USS Pueblo ship. Free political prisoners and vow for a new day in Korea-partnership with the south. China send aid too as does Japan. If this happens—Trump should get the Nobel Peace Prize. It could happen.