About time!
If North Korea falls under anyone's area of responsibility, it would be China. They are in range of NK missiles right now.
It has been really irritating to see people calling for us to take unilateral action on NK while nations like China that have a much bigger stake in this, and much more influence on NK than we do, pretend they have nothing to do with it.
Ideally, it would be great if the U.S. could largely sit this out (with appropriate diplomatic support where necessary) while China, Japan, and other local nations take a lead.