It's a bit amazing, it's Pompeo whom is being questioned about and not John Bolton.
Here, this is probably what this is about:
Why is Pompeo so controversial?
Last week, during a US Senate subcommittee hearing, Mr Pompeo was asked if he would agree with descriptions of Mr Kim as a "tyrant", he then responded: "Sure, I'm sure I've said that."
This was met with a strong reaction from North Korean foreign ministry official Kwon Jong-gun, who said that Mr Pompeo "spouted reckless remarks, hurting the dignity of our supreme leadership... to unveil his mean character".
Mr Kwon also blamed Mr Pompeo for the abrupt ending to the Hanoi summit.
https://www.bbc.com/news/world-asia-47971164
This is also probably why President Trump answered that Otto Warmbier question that way 2 months ago after the summit in Vietnam. You don't want to upset the NK regime. I just saw a bit of the 'Killing Fields' and I noted the concentration camp of the Khmere Rouge. Maybe better said a death camp. It might not be North Korea's, but I'm sure, for human rights, NK's are still horrid.