For the time being China, Russia, South Korea, Japan, and USA’s interests are aligned in terms of denuclearization...
The long term is a different story. Post de-nuclearization, what then? A unified Korea would have complex ramifications. For Americans: the attention will be focused on U.S. troops presence on the DMZ. Somehow we need to make sure that Korea is no longer a costly burden, yet does not become a new threat closely allied with our other adversaries.
And in Asia, while a nuclear North Korea is a threat, a “united” and prosperous single Korea may not be a welcome new reality by its neighbors either...
Their interests are aligned in terms of exploitation of NK.
As is Kim’s.