Update: Now North Korea says its offer is different from the one Trump described. It says it was asking only for partial sanctions relief in exchange for closing one nuclear facility — not full relief, as Trump had said. Secretary of State Mike Pompeo, it bears noting, did not correct Trump’s claim at their joint news conference.

President Trump has changed the American political calculus when it comes to talking to dictators. His efforts to secure a denuclearization deal with North Korean leader Kim Jong Un have even won over some critics. And although it’s tempting to label his decision to walk away from this week’s summit with Kim a failure, it’s worth emphasizing that a big part of negotiating is being willing to walk away. No deal is better than a bad deal, and Trump is serving notice that he’s not just going to agree to something for the sake of cutting a deal. That’s probably a good sign.

But there is a real question now about just how feasible that deal is — and whether it was truly worth a second summit with Kim.

In explaining his decision to walk away, Trump said that the deal was on paper and “ready to be signed.” But then he proceeded to say that the hang-up was that North Korea wanted all sanctions eliminated for getting rid of just one nuclear facility — Yongbyon.

Those two statements don’t make any sense next to each other. As The Washington Post has reported, closing just one nuclear facility, even a big one such as Yongbyon, would still leave North Korea with a large nuclear arsenal. And that means North Korea was proposing something that falls far, far short of the demand the United States made when this whole process started: that any sanctions relief would be contingent upon the full, verifiable denuclearization of North Korea.

To this point, there is no indication that North Korea is seriously entertaining such a thing; the offer Trump described suggests that the two sides are not even close to agreeing on the core principles of a broader deal. And agreeing to a framework that involved full denuclearization is merely the first step; the question from there would be how it would happen and how it could be verified.

If North Korea hasn’t agreed to even that core principle, what is Trump doing flying halfway around the world to negotiate the specifics?

As with any negotiation, the initial demands can be relaxed. And it seems as though there is some give in the United States’s position. In recent weeks, Secretary of State Mike Pompeo has suggested that some sanctions, just not the big ones the U.N. Security Council instituted in 2017, could be relaxed before full denuclearization is achieved and verified. That’s a shift from his testimony to Congress in July in which he said that no U.N. or U.S. sanctions would be relaxed shy of full denuclearization. Other reports indicated a similar loosening of demands.

But even as amended, it doesn’t seem to be anywhere close to what North Korea is willing to countenance, at least according to how Trump characterized it in his news conference:

Q: So can you just give us a little more detail? Did you get into the question of actually dismantling the Yongbyon complex?
TRUMP: I did. Yes. Absolutely.
Q: And does he seem willing, ultimately --
TRUMP: Totally.
Q: -- to take all of that out?
TRUMP: Sure. Totally.
Q: He does? He just wants all the sanctions off first?
TRUMP: He would do that, but he wants the sanctions for that. And as you know, there’s plenty left after that.
Q: So he was willing to Yongbyon, but you wanted more than that? I assume --
TRUMP: We had to have more than that, yeah.

There is a reason polls show that people like the idea of negotiating with dictators: They like the idea of negotiating, period. What could be wrong with talking and trying to solve problems? But the fact that Kim has now gotten two audiences with Trump — not to mention Trump’s hyperbolic praise of him — can’t help but legitimize him on the world stage. U.S. negotiators need to be wary of meeting just for the sake of a dictator’s photo op. Trump even gave Kim a personal pass Thursday regarding the death of Otto Warmbier, saying he believes Kim when he says he wasn’t involved in the American’s torture in a North Korean prison. That is a not-insignificant concession.

There has long been a sense among experts that this is simply Trump throwing something at the wall and hoping it’ll stick. Often it seems as though he’s trying to land a legacy item, and the people around him are humoring him because they can’t do anything to stop him from meeting with Kim (apart from trying to prevent him from signing a bad deal).

We don’t know precisely what brought Trump to Vietnam to talk some more, but if North Korea’s offer is and has been what Trump described, there have to be real questions about whether it’s serious. And if Kim moved the goal posts on previously agreed-to core principles, it would seem that it might warrant a stronger response than simply walking away from a summit.