One thing that is known is that North Korea knows they cannot win a war against the South. The proof of that is how they have organized their military. Those artillery pieces on the border are a one-shot threat. They get about 72 hours to inflict as much damage as possible, until US air power takes them out. If they play this card, they forgo their opportunity to send their infantry and armor south. Instead, the North will have to wage a defensive war, hoping the South elects a negotiated end rather than an invasion.
This means their best card to play in this game just about guarantees their destruction, either from a land invasion or an extended air campaign. It would certainly end the Kim family dynasty. That makes the threat significantly less credible. The US can pressure China or make a deal with China, to get help putting the screws to the Kim regime, knowing that the Koreans only have a doomsday card to play. In other words, the doomsday card prevents a US invasion, but does not prevent economic war.
And what of those Other Players, anyway?
Of course, it’s possible that the math has changed for the Chinese. Right now is peak China economically and demographically. Now is the best chance they will have to resolve their Korean problem. A decade from now, when China has an aging population and the North Koreans have the ability to strike Beijing, the Americans may not be interested in helping with this problem. The best time to address tough problems is when you have the resources to address them. There is no better time than now for China.
There’s also the Trump factor. Previous presidents have been willing to accept the options presented to them by the foreign policy establishment. Trump is psychologically incapable of accepting the options presented to him for anything. Everyone who has done deals with him says the same thing. Trump thrives under pressure, so he puts everyone under pressure. He’s sure he can wheel and deal with anyone under pressure, so that’s how he changes the negotiating table. He creates uncertainty and puts everyone under the gun.
That seems to be what he is trying to do with Asia. On the one hand, he is encouraging Japan to build out their military and take a more active role in policing the region. This puts enormous pressure on China. He’s helping the South Koreans get ready for war, which puts pressure on the North and on their relationship with China. All of a sudden, the US is doing things very different in Asia. Trump’s willingness to change course on a dime adds an air of unpredictability to him, which always makes Asian leaders nervous.
Maybe “under the gun” wasn’t the best possible choice of words. But that’s Trump’s M.O., and always has been.