Graham, a Trump ally, said he worked closely with Bolton to reshape Trump’s exit from Syria.

“The moment I heard we were pulling out, I called Bolton. I said, ‘What the hell is going on here? This is a disaster,”’ Graham said in an interview. He and Bolton then worked together to discuss with Trump how they could achieve his goal of withdrawing U.S. forces while protecting Kurdish allies and preventing a resurgence of the Islamic State.

Trump’s feelings about Bolton aren’t as warm as those for Secretary of State Michael Pompeo, a sometime Bolton rival. Bolton comes from the Republican establishment Trump ran over on his way to the White House, and the president passed over the former UN ambassador twice for national security adviser before choosing him to replace H.R. McMaster.

Another potential flashpoint between Bolton and Pompeo is Afghanistan, where the U.S. special envoy, Zamay Khalilzad, is under orders from Trump and the Secretary of State to negotiate a peace deal with the Taliban.