Trump is no different than previous presidents who have taken their victory lap after "agreements" with the Norks. The only difference is that with the twitter account it's a lot more in your face.
One of the people I know through a mutual friend is Pentagon policy analyst and she's spent years working on negotiating teams on various subjects in various locations.
She's really down on the whole summit thing, and keeps decrying how it's going to be a failure. In discussing (debating) this with her it's become painfully obvious that she's somehow viewing the repeated diplomatic/policy/treaty negotiation failures of the past 60 years as successes, and thinks we should continue on along the same track.
She's seeing only failure in the leader-to-leader approach, to which I replied SO FREAKING WHAT? If it fails, it fails and joins the huge list of failures brokered by negotiators over the decades.
She refuses to see any potential upside, which helps cement my belief that no matter what comes out of this process, even if it results in continued meetings, extended negotiation, and tangible results, the left (and she is DEFINITELY the left) will never admit that it was anything other than a failure.
As I flat out ask her... Given the abject history of failures of your kind, what's the problem with trying a new approach?
I'm still waiting for a response to that question.