Do you trust this man? Photo: Olivier Douliery/Getty Images

At a freewheeling Pennsylvania rally Saturday night, President Trump boasted about his unprecedented upcoming meeting with Kim Jong-un, which the White House had announced with great fanfare this week — and which may or may not actually end up happening.

“I think North Korea is going to go very well,” he said. “I think we will have tremendous success … they promised they wouldn’t be shooting off missiles in the meantime, and they’re looking to de-nuke. They’re gonna be great.”

But on the Sunday morning talk shows, senators were singing a different tune. While cautiously optimistic about the meeting as a whole, they’re understandably worried that Trump will be taken advantage of by a regime that has gotten the better of the United States many times over the years.

On Meet the Press, Senator Elizabeth Warren said that the meeting is a “win” for North Korea. “It legitimizes, in their view, their dictatorship and legitimizes their nuclear weapons program.”

She said she wanted the president to succeed, “but these are very complex negotiations, and what I’m concerned about in these negotiations is we have a State Department that’s just been decimated. We don’t have an ambassador right now to South Korea. We don’t have an assistant secretary for this whole region.”

But it wasn’t just Democrats voicing their concerns about the upcoming tête-à-tête.

On CNN’s State of the Union, Republican Senator Ron Johnson expressed concern that North Korea’s vague commitment to denuclearization may not count as much of a bargaining chip.

CNN anchor Jim Acosta mentioned that North Korea had pledge to denuclearize before, and simply gone back on its word.

“Is the president just being naïve here?” he asked.

“Let’s hope not,” Johnson said uncertainly. “Let’s not be snookered again. Let’s not be Charlie Brown to North Korea’s Lucy. We’ve seen this movie before — that’s why we’ve called on Trump to maintain the maximum pressure campaign.”

Another GOP Senator (and frequent Trump critic), Jeff Flake, told Chuck Todd on Sunday that it was “a little bit worrisome” that no diplomatic work had gone into the meeting, which would typically be the capstone to painstaking diplomatic efforts, not an opening gambit.

And last week, Trump ally and bombing enthusiast Senator Lindsey Graham issued a statement that supported the president while seeming to acknowledge that he is very vulnerable to being taken advantage of.

“The worst possible thing you can do is meet with President Trump in person and try to play him. If you do that, it will be the end of you — and your regime,” he said.

All these concerns are eminently reasonable. As the Ne York Times reported on Saturday, President Trump accepted Kim Jong-un’s invitation through a South Korean envoy on the spur of the moment, and against the wishes of his advisers. He didn’t seem to understand that the North Korean regime has desired a face-to-face meeting with a U.S. president for decades, and that his acceptance already counts as a major propaganda win for Kim. And his impulsive “yes” ran against years of U.S. foreign policy doctrine, which mandated that North Korea give up its nuclear weapons program altogether before the U.S. would dignify it with a meeting. (North Korea has agreed to suspend tests in the run-up to the talks, but nothing more.)

It’s true that, at this point, such demands are less realistic than ever, given the rapid advancement of the country’s weapons program in recent years. But it’s also true that the North Korean regime has a long, distinguished history of strategically outmaneuvering America. It has gone against multiple pledges to discontinue its nuclear program, and defied sanction after sanction since it launched its first nuclear weapon in 2006. And the last time the U.S. sent a high-level diplomat to the country — when Secretary of State Madeleine Albright flattered Kim Jong-il in 2000 — it was viewed as a public-relations coup for the Koreans.

So there’s a strong likelihood that, even if the meeting happens, North Korea will continue — or even ramp up — its belligerent behavior while basking in the legitimacy of being taken seriously on the world stage.

In that scenario, Trump will end up being just another patsy for the regime. Perhaps most dangerously for the world, he’ll be left feeling embarrassed. And if there’s one emotion that causes our president to lash out in anger with unpredictable consequences for the world, it’s humiliation.

Thanks to the childlike emotional makeup of the most powerful man in the world, the senators are right to worry.