Incentives

As long as the North Koreans keep up with their provocations, the Americans will continue to look to the Chinese to solve the problem, and Trump will back down on his threats of trade sanctions on China as China provides the only hope of a Korean settlement.  As long as they dither, the Chinese avoid American trade sanctions. 

The only route to a possible settlement that the North Koreans can live with is to continue to provide some reason for the Americans to want to settle, which encourages more provocations to provide an incentive to pay attention to the issue.  The new sanctions are stringent enough that they will encourage further North Korean acts to gain attention, as attention is the only possible path to getting the negotiated deal they want.

The North Koreans, and the rest of the world, remember that Gadaffi gave up his nukes, and got a bayonet up the ass from the neocons for his troubles, with his country laid waste.  The lesson learned from the neocons - not to mention the horrors the American inflicted on Korea during the Korean War - is that you can never, in any circumstances, give up your nukes.  'We came, we saw, he died' (and note the horror-movie cackle).  Killary would have already started WWIII over this, no question, so the phony alarm of the Clintonistas to Trump's rhetorical flourishes is disgusting.  Americans are never going to get a negotiated deal anywhere now if part of it is giving up nukes.

Essentially, the Americans have set the incentives up in this case completely backwards, encouraging brinkmanship and chaos.