Joel S. Wit, who has negotiated with North Koreans for over twenty years, has a very interesting NYT piece on that topic, here is one excerpt:
The North Koreans may know a lot about the outside world, but they don’t know everything, even about the United States, their main adversary. In one meeting, an official asked, “Why do the president and secretary of state keep saying that the United States will not allow North Korea to have nuclear weapons when in fact you are not doing much to stop us?” He deduced that there must be a hidden agenda. “It’s because you want us to have nuclear weapons as an excuse to tighten your grip on South Korea and Japan, your two allies.” We responded that there was no hidden agenda and that the United States really did not want the North to have those weapons. I’m not sure we convinced him.
The piece is interesting throughout, most of all Wit stresses their realism and sophistication as negotiators, and urges us not to think of them as lunatics.