The (Ex) Washington Realist

How enthusiastically is China going to enforce sanctions on North Korea?

Folks, let's walk through the calculus here.

Does North Korea threaten China? No. Is China concerned that North Korea will deliberately transfer nuclear technology to enemies of Beijing? No.

Is China concerned that nuclear technology will leak in an uncontrollable process from North Korea? Yes. North Korea may not arm Uighur groups or Taiwan, but there's a point on the international black market supply chain where Pyongyang loses control (as it did with A. Q. Khan).

Is China concerned about the U.S. taking forceful action which could destabilize East Asia? Yes.

This is the way in which Beijing's national interests are being formed and means that China will continue to "do enough" on North Korea to prevent major transfers of technology and to forestall a U.S. armed response.