Navy Secretary John Phelan will be leaving the administration effective immediately, the chief Pentagon spokesman, Sean Parnell, announced on Wednesday evening. It’s unclear what prompted Phelan’s exit or whether it was his choice.

“Secretary of the Navy John C. Phelan is departing the administration, effective immediately,” Parnell said. “On behalf of the Secretary of War and Deputy Secretary of War, we are grateful to Secretary Phelan for his service to the Department and the United States Navy.”