I think China wants in on the DPRK's vast mineral resources, which are not insignificant.
Furthermore, supporting North Korea's acts of random omnibelligerence is a good reminder to Japan, who are poised to intervene and lay waste to China's most heavily populated and economically successful region if demanded, that such actions are not without consequence.
I’m aware of the importance and value of rare earth elements. I did not, however, know that North Korea held the world’s largest deposits. Thank you for that specific information.
That, however, just makes Kim Jong-un’s behavior even more perplexing to me. I mean, I did not know the man is sitting on top of a vast fortune, all the while allowing his people to live with the threat of starvation hanging over their heads. It’s easy to say that the guy is crazy, but really, what the hell?
All that military activity in the South China Sea, etc. has me equally baffled, even more so after reading the article you posted. But, I’m going to take some time to gather my thoughts, and I’ll post something more on that subject later on.
North Korea's political behaviour is constrained by specific internal conditions. Specifically the North Korean military has a very large say in North Korean politics, and maintaining a state of affairs where North Korea is considered hostile and suspect by the world at large strengthens their hand in internal politics. North Korea could open itself up to trade, liberalize...but that would weaken the military to the benefit of the North Korea Workers Party who, in this scenario, would quick likely develop along similar lines to the Chinese Communist Party.
My thinking is that China would like to see such a development, and indeed some of the early developments in North Korea when Jong-Un assumed power suggested this may be the case. However, political leaders in North Korea who could've reigned in the military were either sidelined, or killed by Jong-Un for bizarre and implausible acts of "treason". Jong-Un also wasn't seen publically for several months. IMO, a palace coup occured, with the military taking firm control of the regime and leaving Jong-Un as a figurehead.
China isnt thrilled about that outcome, I suspect, but so long as North Korea's military is willing to stress its beserker opposition to South Korea, Japan and America, it acts as a potential headache for any future naval war between Japan and China. So they're willing to live with it, for now.