Your response to NK is IMHO exactly what NK wants. They think that having nuclear weapons will get them a seat at the table. Which table I'm not sure. What they want from that point I suspect is more than just elimination of sanctions.
Would it be so terrible to end sactions against North Korea? Trade should rise the middle class North Koreans up, and the last thing a wealthy middle class wants is war. A well fed and housed middle class seems the best insurance against war possible.