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The US pulling out of North Korea summit by itself and talking tough citing American military strength is the best decision now to shake up China. As Trump said Kim changed his decision about the meeting only after meeting Xi the second time. Looks like China has met it's match in the US now. A totally unpredictable, faking, lying, borderline dictatorial regime just like the CCP. They thought they could play the US the way they do with others using North Korea but seem to have failed miserably. Now the showdown is going to begin for their companies and economy. And if the US does take military action on NK, it will be a disastrous set back to China's ambitions of anything in the next 10 years.
I also think Kim Jong Un will come around and ask for a summit with the US angering China. I believe this guy is really ready for long term truce and peace with the US. But China wants to keep control of DPRK for various reasons. It may be in his best interests to ditch China for the US now. And he may actually do that. But when he does that let's be ready for "incursions" by Chinese troops into North Korea claiming "historical territory". They will open a border dispute immediately to take control of diplomacy with NK.
I think Trump's withdrawal is just for show, he wants to meet with NK on the US's terms. From what I've heard, NK has been trying to reach out to the States for quite a long time