Barr has been meeting with the U.S.’ closest foreign intelligence allies in recent months, making repeated overseas trips as part of an investigation he is overseeing into the origins of the Russia probe and whether any inappropriate "spying" occurred on Trump’s campaign.

As part of that investigation, Barr and John Durham, the federal prosecutor he appointed to conduct it, have been probing a conspiracy theory for which there is little if any evidence, according to several people with knowledge of the matter: that a key player in the Russia probe, a professor named Joseph Mifsud, was actually a Western intelligence asset sent to discredit the Trump campaign ‐ and that the CIA, under Brennan, was somehow involved.