Top aide to former Defense Secretary James Mattis also resigns: report
Defense Secretary James N. Mattis and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, brief reporters on the current U.S. airstrikes on Syria during a joint news conference at the Pentagon, April 13, 2018. DoD photo by Army Sgt. Amber I. Smith

The top aide to former Defense Secretary James Mattis, who resigned in protest over President Donald Trump's plan to withdraw forces from Syria, will also resign, reports Axios.

Rear Adm. Kevin Sweeney was chief of staff for Mattis, and insiders worry that there will now be a lack of institutional knowledge inside the Pentagon.

"In normal times, the resignation of a chief of staff following the departure of a secretary of defense would not only be seen as unsurprising, but as expected," former Pentagon official Brent Colburn told the outlet. "These are not normal times. With so many leadership gaps in the building, and so much uncertainty about future leadership, this will just add to the growing sense of instability in an institution that thrives on predictability."