I think we need to have a quiet heart-to-heart talk with China. China needs to understand that the U.S. will never live under the shadow of a nuclear missile equipped North Korea. Never. In this heart-to-heart talk, I would implore the Chinese, in the most gravest of terms, to do something about North Korea. And I would tell them that if they don't, eventually we will, and we will use every asset at our disposal. Every asset. I would warn the Chinese that our war against North Korea will be started and finished in the same day.
They are also slowly pushing out their borders in the South China Sea. Creating islands and putting defenses on them and claiming them as sovereign territory. Ships are then required to keep a distance from the islands and the Chinese claim the fishing and mining rights to those new areas. They are at serious odds with the Haig Courts who have ruled what they are doing is illegal. China, of course, says they do not recognize these courts. https://www.nytimes.com/2016/07/13/world/asia/south-china-sea-hague-ruling-philippines.html This is not a good situation and (all politics aside here), our military is in the worst shape it has been in a very long time. China probably sees an America divided, easily hacked and manipulated, in serious debt and a new Administration in the office. They will pushback very hard on us. They are curious to see what they can get away with. IMO.
Agreed, the best diplomatic foot forward is an understanding with the Chinese on North Korea. The more you look at it, the more necessary it becomes to have one of the Eastern Powers as a strongly committed US ally. I'm more than up for making China that ally. I would beseech China that if it couldn't get NK to reduce its nuclear weapons, it should at least tell NK to sign the NPT and agree to watchdogs. The NPT prevents the use of nuclear energy for weaponization purposes and for warfare. The US for example is a signatory of the treaty, as is most of the world. And like you said, if China could not get them to follow in these steps, or to reasonably assure the domestic peace of the US and other Asian neighbors, then we would have no choice but to enter the stratosphere. Even if this means facing the Chinese Front itself.
If the Chinese couldn't get the North Koreans to sign the NPT and agree to watchdogs, I would suggest to them that they do something else - like a regime change. I would assure them, however, that North Korea must end its missile tests and nuclear program. I would assure them that if the North Koreans ever reach a point where they can threaten the U.S. with weapons like that, we will take action because we will not live under a North Korean nuclear shadow. That is not negotiable, and it will never happen. I would also assure them that our intent would be to make this a one day war. There would be no invasion "after". The Chinese may keep North Korea within their sphere of influence. But if they don't end the nuclear threat, we will.
Agreed, we don't want NK territory or really even any territory in the Asian Sphere. We don't have any rightful claims to any outside of Hawaii and so, we won't even make them. The future of Korea, would be a unified Korean State under South Korea's direction and the advancement of the North into the 21st century. I'd tell China that unified Korea by no means is obligated to the US, nor should it be threatened or intimidated by any other Asian Power.
Because it won't happen. No one that has spent decades trying to build a nuclear weapon and billions to do so is going to sell one.
China's great fear is not the supposed "refugee crisis on their border" that people claim is the reason they hate the thought of North Korea collapsing. China's great fear is a major economic (and potentially military) power on their border with absolutely no reason to look favourably at the Chinese. Which is what a United Korea (under the leadership of Seoul) would be within 20 years of its unification.
Nothing came from the meetings in China over North Korea: http://www.reuters.com/article/us-tillerson-asia-china-idUSKBN16Q038 The Chinese basically deflected, which is what they have been doing for a long time. China will enforce UN sanctions because keeping North Korea poor and under their thumb is greatly advantageous to them.