It's not that complicated. To get the best concessions you come with biggest chips of your own to trade. Even if NK's intention was to negotiate from day one, t

It's not that complicated. To get the best concessions you come with biggest chips of your own to trade. Even if NK's intention was to negotiate from day one, they would have gone for nuclear weapons first, given that prior negotiations did not net them satisfactory concessions. What's changed is that they believe they have big enough chips now and Trump is high-variance enough that the gamble is worth it.