Mike Pompeo can’t be as credulous as he pretends to be :
I was there. I was there when [Kim] said it. He made a personal commitment. He has his reputation on the line in the same way that we do, that says we’re going to create a brighter future for North Korea. We’re going to denuclearize just as quickly as we can achieve that.
Kim may have said something like this, or maybe he said something different that Pompeo misunderstood to mean this. Regardless, that doesn’t mean that North Korea is going to do what Pompeo says it will. The statement from the summit doesn’t support Pompeo’s interpretation, and so he has to pretend that lots of other things are implied or “understood” that haven’t been written down. Pompeo bristled  when he was questioned about the weakness of the language of the summit declaration, because I suspect he knows deep down that he is defending an untenable position and doesn’t have good answers to basic questions about the substance.
Pompeo denounced  the very good nuclear deal with Iran as a surrender by the U.S. Now he is claiming that the U.S. can trust North Korean intentions just because Kim told him something. Kim likely doesn’t care about his international reputation in “the same way that we do,” and he also has to keep his own domestic constituencies satisfied and can’t afford to be seen as capitulating to the U.S., much less doing so as quickly as possible. Pompeo ignored Iranian compliance with the JCPOA despite the use of the most rigorous and intrusive verification mechanisms anywhere, but he expects the public and Congress to accept that North Korea should be trusted without any verification because their leader offered him some assurances in private. The glaring hypocrisy is galling, but it is the intellectual dishonesty on display from members of this administration that is truly breathtaking.