In early 2002 the idiot George W. Bush publicly called Iraq, Iran, and North Korea an “axis of evil”. What did that statement do besides putting those nations on guard?
Trump is taking the right path here.
I recall when during his first address to the UN, Trump called Kim "little rocket man", and his chief of staff John Kelly utterly betrayed him by doing a face palm in front of the cameras of the world. But Kim apparently was amused by the reference to Elton John. Kim had been educated in Switzerland and was familiar with Western pop music.
Kim and Trump met at the NK-SK dmz line, and as they flew over NK by helicopter, Trump pointed out to Kim the great shoreline and other places that could have profitable real estate development, fascinating Kim, who has since approved some limited resort development. Step by step...
I'm fairly certain that our President is well aware of the risks and dangers of the Kim regime; but he has made the most of the opportunity, and Kim's constant nuke threats that characterized his relationship with Dubya have diminished and all but disappeared.