In a way, they have this attitude because they are used to only getting slap on the wrist for their egregious acts.
I think Trump has sent a number of messages in various ways that North Korea is going to be denuked. Nuking them in the process is one option. They can cooperate and generate other outcomes.
Un Security Council meeting going on now....so far all on the same page....though China still wants to chip away at N.Korea by tit-for-tat negotiations as they’ve always done....they do not think China should have to do this themselves.
No doubt China would still like to go back to the same old way of dealing with N.Korea....but doesn’t appear the Security Council is on their page.