President Donald Trump said in an interview segment released Sunday that he was unsure how long Defense Secretary James Mattis planned to stay in his administration.

“Well, I don’t know,” Trump said when asked whether the Pentagon chief would be leaving in an interview on CBS’s “60 Minutes.” “He hasn’t told me that.”

Trump said the two maintained “a very good relationship,” but he allowed for the possibility Mattis would leave.

“I think he’s sort of a Democrat, if you want to know the truth,” Trump said in the interview slated to air Sunday night. “But General Mattis is a good guy. We get along very well. He may leave. I mean, at some point, everybody leaves. Everybody. People leave. That’s Washington.”

Army Col. Robert Manning, a spokesman for the Pentagon, issued a statement in response to the President’s remarks.

“Secretary Mattis is laser-focused on doing his job — ensuring the US military remains the most lethal force on the planet,” the statement read.

In his last years as commander of Central Command, Mattis was at odds with the Obama administration over its policy toward Iran, with the Marine general taking a harder line about pursuing action against Iran than the White House wanted.

Mattis left Central Command and retired from the military in 2013. A source close to Mattis previously told CNN that he rejected overtures from Hillary Clinton’s campaign to work in that administration had she won.

Following his victory in 2016, Trump tapped Mattis to be defense secretary, a position he secured after Congress passed a waiver allowing him to take the civilian post shortly after his retirement from the military. CNN reported in June on differences between Trump and Mattis that was leading to anxiety in the Pentagon and raising the possibility that Mattis might eventually leave the administration.