It's all gone south in North Korea!
It started when US VP Mike Pence warned Rocket Boy, Kim Jong-un, that he could end up like Colonel Gaddafi in Libya. In case Libya has faded from your memory, let me remind you. In 2011, as part of the "Arab Spring", the West provoked Libyan rebels (ie, people not members of Gaddafi's tribe) into overthrowing the regime. Gaddafi fled from Tripoli to his hometown of Sirte where he was holed up for a while.
Eventually the rebel build-up was too strong and he made a run for it in a small convoy but he was captured by rebels. They stuck a bayonet up his rear end (graphic video on YouTube) and later killed him.
It seems Rocket Boy did not like Pence's comparison. He got is own VP (Kim Kye-gwan, presumably a relative of Rocket Boy as they share the family name "Kim") to be rude about John Bolton, Trump's national security advisor, declaring him to be repugnant.
So President Trump canceled the meeting he was due to have with Rocket Boy in June to discus nuclear disarmament.
Then Rocket Boy blew up one of his own nuclear installations.
Why this weird behaviour?
Well, the important thing to remember is that North Korea develops nuclear weapons for one reason only: to trade them away for food and other aid. So Rocket Boy does need talks to resume, far more than Trump does. Trump's only skin in the game is that he might get a Nobel Peace Prize if he solves the Korean situation.
So Rocket Boy has shown his contrition by destroying one of his own installations. But he has others so this is not a big concession. However, he will certainly be back at the negotiating table before long. And Trump knows this and is him playing like a fish.