"the mercurial, erratic, and unreliable obstacle to peace"

Good analysis on Trump pulling out of a summit with North Korea:

"As a result he has every incentive to simply continue to bilaterally negotiate with Kim to achieve Moon’s and Moon’s government’s understanding of the ROK’s national interest. By impulsively deciding to grant Kim a summit based and now impulsively pulling out of that summit because of some tough talk, the President seems to think that his maximum pressure campaign got him the opportunity for the summit and can now simply be reimposed and once again achieve positive goals. The problem, of course, is there is no evidence that the President’s maximum pressure approach actually contributed to or set the conditions for Kim to pursue a bilateral US-DPRK summit, which is something Kim, his father, and his grandfather have been trying to achieve for decades. . . .

Kim has largely already gotten what he wanted. He got the President to agree to meet with him. He got two photo ops with Secretary of State Pompeo. He got the President to call him an honorable man. And he got the President to call this off, making the US look like the mercurial, erratic, and unreliable obstacle to peace. It is important to remember that there are a whole bunch of foreign reporters in the DPRK right now because they were there to observe and report on the destruction of the DPRK nuclear test facility. If we’re very lucky, Kim won’t decide that he too can play the “or else” game as well and scarf these folks up as hostages to use as bargaining chips."

tl,dr: Kim Jong-un drank Trumps milkshake.  Because of course he did.