In a few months, a former U.S. president — Jimmy Carter or Bill Clinton — may be asked to travel to North Korea in pursuit of military denuclearization.
In 1994, Carter did exactly that. Meeting personally with then-maximum North Korean leader Kim Il Sung, the founder of the Democratic People's Republic of Korea, in Pyongyang, the former U.S. president hammered out an understanding that was to lead to the 1994 Agreed Framework negotiated in Geneva.
The key to the overall accord was the top-down approach to diplomacy. This is virtually the only method for achieving negotiated agreements with a dictatorship like North Korea. Dealing with lower-level emissaries will inevitably be frustrating, because they inherently lack the authority and negotiating room.
Even senior North Korean officials — much less mid-level ones — are afraid of exhibiting an independence or freedom of thought in even private negotiations. (They assume, properly, that every such conversation is bugged.) They are afraid of losing their lives: For in a feral dictatorship like North Korea's, there is only one source of wisdom and political correctness, and that comes from the boss.
This leads to the second problem. The current boss of North Korea (as far as anyone knows) has been recovering from a severe medical setback, probably a stroke or strokes.
The question remains: Will the North Koreans ever truly abandon their nuclear-arms program? The answer is yes, but only if (1) the price in aid is high enough, and (2) some very high-level American travels to Pyongyang to nail down the framework of the deal with whoever is then the leader of North Korea.