“The problem with John (Bolton) is that it’s a national security problem,” Trump said as he prepared to leave the World Economic Forum in Davos, Switzerland, to return to Washington, where opening arguments were set to begin in the historic proceedings.

“He knows some of my thoughts, he knows what I think about leaders. What happens if he reveals what I think about a certain leader and it’s not very positive?” he said, adding that Pompeo testifying would also be a risk.

“You could call it presidential prerogative,” Trump said. “The way I look at it, I call it national security, for national security reasons. Executive privilege.”