Analysis: What went wrong for Trump in North Korea? Everything.
But the president, fearing that the North Koreans might beat him to the punch, wanted to be the one to cancel first, multiple officials told NBC News.

“There was no hint of this yesterday,” a person briefed on the summit preparations said, calling Trump’s decision “high risk, high reward.”…

The move exposed significant disagreements among the president’s top advisers. Several administration officials said Pompeo, who has taken the lead in negotiating with the North Koreans, blamed Bolton for torpedoing the progress that had already been made. Pompeo flew to Pyongyang twice, met personally with Kim and helped secure the release of three Americans who had been held there. Bolton, a longtime national security hawk who has publicly advocated for regime change in North Korea, was integral, these officials said, to convincing Trump to back out of the summit.