Seems like China might be the most powerful component in this entire mess. Most likely China likes to keep US distracted with NK and also doesn't want NK and SK united because then they would have another competitor.
https://www.google.com/amp/s/amp.bus...h-korea-2017-3
The above article raises several points including "If China unilaterally denuclearized North Korea to head off a US strike, this would only vindicate that claim, and raise questions as to why China allowed North Korea to develop and export dangerous technologies and commit heinous human rights abuses." And that "China could bring forces into North Korea to act as a tripwire." You know, stuff that makes you shake your head.
A side note not directly related to the article: I'm not sure how debt works exactly when is comes to what the USA owes China. The U.S. debt to China is $1.102 trillion, as of May 2017. According to Google. I mean if China does not have the US back 100% could we not just say forget about ever seeing one cent of what we owe you?