In order to make it WWIII, somebody would have to side with crazy North Korea.
Don’t see that happening. Maybe Venezuela.
Obviously we don’t know what discussions/negotiations are occurring behind the scenes, but I would hope that it is being made clear to the Chinese that this is entirely unacceptable to us, and that if North Korea continues down this path we will have no choice but to ensure nuclear armament of Japan and South Korea. Do it privately, to allow fat Kim to save face, but make it clear to him and China that there is no scenario in which he survives in power while he continues down this path.