Hung Cao to take over as acting SECNAV after Phelan’s unexpected exit from Trump administration

John Phelan is departing his role as secretary of the Navy, effective immediately, and Hung Cao will step in as acting SECNAV, Pentagon chief spokesman Sean Parnell announced on social media late Wednesday.

Phelan’s surprise exit comes a day after he delivered a keynote address at the Sea-Air-Space symposium, in which he touted plans for a next-generation battleship, one of President Donald Trump’s signature military modernization initiatives.

“Secretary of the Navy John C. Phelan is departing the administration, effective immediately,” Parnell said in a statement.

“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,” he added. “We wish him well in his future endeavors.”

Parnell said that Cao, who has been serving as the Navy’s No. 2 civilian in the undersecretary role, will become the acting SECNAV.

Parnell’s statement did not provide a reason for Phelan’s departure. The Trump administration has removed several high-profile Pentagon officials without providing a public explanation. Most recently, Gen. Randy George was ousted as Army chief of staff by Defense Secretary Pete Hegseth.

In response to a query about why Phelan is departing, a public affairs official in the Office of the Secretary of the Navy referred DefenseScoop to Parnell’s statement.

Last year, Phelan tasked Cao as chief management officer with leading and synchronizing the modernization of the Navy’s unclassified IT systems and critical defense business systems.

Cao, who was nominated for the Navy undersecretary position last year by Trump, is a U.S. Naval Academy graduate and was commissioned as a special operations officer, serving as a diver and explosive ordnance technician. During his long career in uniform, he deployed to Iraq and Afghanistan during the post-9/11 wars. He also worked at the Pentagon, including as the section head for the budget programming division in the Office of the Chief of Naval Operations, according to his LinkedIn profile. After leaving the Navy, he ran unsuccessfully for U.S. House and Senate seats as a Republican candidate in Virginia during the 2022 and 2024 election cycles, respectively.

In his written statement to the Senate Armed Services Committee before his confirmation hearing last year, Cao told lawmakers that there’s a generation of young people that are eager to serve.

“They grew up in the digital age where technology evolved at quantum speed. They deserve the best training and weapons available. Their intrinsic desire to solve problems using technology should not be stifled by red tape,” he wrote.