Secretary of the United States Navy John C. Phelan resigned effective immediately, according to an announcement from the Department of Defense on Wednesday. Officials thanked him for his service and said they wished him well in his future endeavors.

Undersecretary Hung Cao will assume the role of Acting Secretary of the Navy. The department did not provide a reason for Phelan’s departure.

Phelan’s resignation comes weeks after Secretary of War Pete Hegseth dismissed the Army’s top officer, General Randy George, along with two other senior generals. Phelan had no prior military or civilian leadership experience in the Navy before being nominated by President Donald Trump in late 2024.