Defense Secretary Jim Mattis joked to President Trump’s next national security adviser John Bolton on the steps of the Pentagon Thursday that he wanted to meet him because he heard he was “actually the devil incarnate.”

“It’s good to finally meet you,” Mattis told the former ambassador to the United Nations. “I heard that you’re actually the devil incarnate and I wanted to meet you.”

Trump appointed Bolton as his national security adviser to replace H.R. McMaster, and his new role will be effective April 9. The announcement was made via Twitter last week.

McMaster announced he would be retiring from the military at the same time he was exiting the Trump White House in April.

Mattis two days ago told reporters that he had no reservations or concerns about working with Bolton, despite the two having different opinions on how to deal with Iran and North Korea.

“I hope that there are some different worldviews. That’s the normal thing you want, unless you want groupthink,” Mattis said. “We’re going to sit down together. I look forward to working with him. Last time I checked, he's an American. I can work with an American, OK?"