Kim Jong Un is manna from heaven for every U.S. Department of Defense Star Wars program manager's budget requests. There is nothing like a rogue nation on the verge of having medium to long range nuclear weapon delivery capabilities that existing technology might actually be able to do something to stop to help fund those anti-missile capabilities.
The only reason that North Korea hasn't been squashed like by bug by Western allied military forces is that this would risk retaliation from either the Soviet Union (now Russia) or China.
It isn't clear, however, that North Korea can rely on those ties to protect it much longer in the face of its aggressive rhetoric and small scale actual provocative acts of hostile military action directed at South Korea. Even a botched missile launch that was more than a test would probably force the hand of the U.S. and cause it to bomb North Korea's potential nuclear and missile facilities into rubble and possibly push it to take military action to unseat its regime as well.
China is a much more market based economy than North Korea and needs trade with the U.S. for its economy far more than it needs anything from North Korea. Indeed, China's political ruling class is to a much greater extent than in the U.S. made up of business chiefs who personally profit from the U.S. business relationship, China's sovereign interests be damned.
The Russians also gets very little from their relationship, such as it is, with North Korea.
From the perspectives of both Russia and China the main objective is not to get anything themselves from North Korea, but simply to keep the United States and its allies from getting any further into their back yards militarily. Also, the defense technology development that U.S. responses to North Korea motivate undermine the effectiveness of Chinese and Russian military programs driving up their military budgets.
The sensible resolution of the current North Korean nuclear weapon threat crisis would be for Russia and China to shut it down without Western involvement. This would allow them to continue to claim that North Korea was within their "area of influence" to keep Western powers out, while defusing the threat to nations whose relationships are much more important to them than the North Korean relationship. Alternately, hidden assurances from Russia and China that they would not come to North Korea's military aid in the face of a U.S. and/or Japanese and South Korean attack if North Korea takes such provacative action would give the U.S. the green light to take military action.
Whether Secretary of State Kerry can connect these dots and work behind the scenes to make this happen is another matter.