Personally, I don't think North Korea is the problem. As with most situations that lead to brinksmanship, to understand it best - follow the money!

As far as money is concerned, North Korea doesn't have any, especially to be able to afford the research, development, testing, evaluation (RDTE) and subsequent manufacture of anything more complex than a lawn mower. The people are woefully under-nutritioned, electric power to the populace fluctuates with the wind, and the national infrastructure is on par with Uganda and Haiti. So, who is paying for all of the missile/nuclear RDTE and providing the logistic support for it?

So, who is funding this folly? When that is determined, the solutions become for obvious.