Chief White House homeland security adviser Tom Bossert resigned Tuesday, one day after conservative hawk John Bolton became national security adviser.

“Tom led the White House’s efforts to protect the homeland from terrorist threats, strengthen our cyber defenses, and respond to an unprecedented series of natural disasters,” press secretary Sarah Huckabee Sanders said in a statement. “President Trump thanks him for his patriotic service and wishes him well.”

Bossert is a career government official who was widely viewed as a steady hand in an unconventional and unsteady White House.

His departure comes after a list of others among Cabinet officials and top West Wing aides, most recently the firing of Veterans’ Affairs chief David Shulkin and the resignation of Hope Hicks as communications director.

The national security staff Bolton inherited, joined by other White House aides, saw former national security adviser Lt. Gen. H.R. McMaster off Friday with a sometimes-loud and boisterous ceremony inn West Executive Drive outside the West Wing.