I believe because China, with the worst problems its had in generations, is cutting support for NK. Trump was a dead end. What is Jong Un to do? He has to do more than bluff now.

Call me crazy, but if China and South Korea could agree to leave North Korea a wasteland both would completely destroy it. Somehow, I believe that will happen. As I mused in my latest story, we can look at the Ukraine and Israel Wars as simple extermination of poor people events connected to the stuff you just wrote about.