America Seizes North Korean Ship, Citing Sanctions Violations
wsj.com
wsj.com
America had her chance to put North Korea back down for years, any time before the acquisition of nukes. Officials from both sides were too cowardly, and America allowed one more nation to get nuclear weapons. One more threat to her citizens, and a completely irresponsible action by every politician.
But for China we could probably sweep through North Korea faster than NK could deploy a nuclear response, assuming they even have a viable weapon.
We could probably trade Taiwan for North Korea, but I doubt that's ever going to happen. We could maybe get away with a promise to leave the Korean Peninsula if they deposed the North Korean regime, but if China accepted that it's because it would weaken U.S. alliances globally (having abandoned a military ally) as well as puts them in a slightly better position to take Taiwan by force. (Alternatively, we could phone Jinping at the very moment we invade NK and promise him that we'll withdrawal all permanent forces, but without formally ending our military alliance with South Korea. An ask for forgiveness rather than permission approach.)[1]
I wouldn't underestimate China's commitment to North Korea. To the old guard in the PLA the defense of North Korea is a pillar of their strategic posture and a matter of honor. As they've died off (and they're not all dead, yet) new leaders have found other reasons to remain committed to North Korea.
[1] With some decent planning I would think we could sufficiently blunt NK's conventional retaliatory capabilities--i.e. the big guns pointed at Seoul. Surely, with a couple of years preparation and sufficient commitment, we could poise ourselves to track and target in real-time their artillery with a massive coordinated strike.