The Pentagon has announced that Navy Secretary John Phelan is leaving his job. In a statement posted to social media, Sean Parnell, a Pentagon spokesperson, said Phelan was “departing the administration, effective immediately.”

No reason was given for the unexpected departure of the Navy’s top civilian official. In a signal of how sudden the latest move was, Phelan had addressed a large crowd of sailors and industry professionals on Tuesday at the Navy’s annual conference in Washington and spoke with reporters about his agenda. He also hosted the leaders of the House Armed Services Committee to discuss the Navy’s budget request and efforts to build more ships, according to a social media post from his office.

Phelan’s departure is the latest in a series of shakeups of top leadership at the Pentagon, coming just weeks after Defense Secretary Pete Hegseth fired the Army’s top uniformed officer, Gen. Randy George. Hegseth also has fired several other top Generals, Admirals and defense leaders since taking office last year.

The firings began in February 2025, when Hegseth removed military leaders, including Adm. Lisa Franchetti, the Navy’s top uniformed officer, and Gen. Jim Slife, the No. 2 leader at the Air Force. Trump also fired Gen. Charles “CQ” Brown Jr. as Chairman of the Joint Chiefs of Staff.

Phelan had not served in the military or had a civilian leadership role in the service before Trump nominated him for Secretary in late 2024. He was seen as an outsider being brought in to shake up the Navy. Phelan was a major donor to Trump’s campaign and had founded the private investment firm Rugger Management LLC. According to his biography, Phelan’s primary exposure to the military came from an advisory position he held on the Spirit of America, a nonprofit that supported the defense of Ukraine and the defense of Taiwan.

Phelan is leaving during a busy time for the Navy. Sea service has imposed a blockade of Iranian ports and is targeting ships linked to Tehran around the world during a tenuous ceasefire in the war. The Navy has three aircraft carriers deployed in or heading to the Middle East, while the Trump administration says all the armed forces are poised to resume combat operations against Iran should the ceasefire expire.

The Navy also has maintained a heavy presence in the Caribbean, where it has been part of a campaign of strikes against alleged drug boats. It also played a major role in the capture of Venezuelan leader Nicolás Maduro in January.

Hung Cao Takes Over As Acting Head

Undersecretary Hung Cao, a 25-year Navy combat veteran who ran unsuccessful campaigns for the US Senate and House in Virginia, is taking over as acting Head of the Navy.

Another Trump loyalist, Cao ran a failed US Senate bid in Virginia to try to unseat Democratic Senator Tim Kaine in 2024. He had Trump’s endorsement in the crowded Republican primary and gave a speech at the 2024 Republican National Convention. Cao’s biography includes fleeing Vietnam with his family as a child in the 1970s. In a campaign video for his Senate bid, he compared Vietnam’s communist regime during the Cold War to the administration of Democratic President Joe Biden. During his one debate with Kaine, Cao criticized COVID-19 vaccine mandates for service members as well as the military’s diversity, equity and inclusion efforts.

When he ran for Congress in Virginia in 2022, Cao expressed opposition to aid for Ukraine during a debate against his Democratic opponent. “My heart goes out to the Ukrainian people. … But right now we’re borrowing $55 billion from China to pay for the war in Ukraine. Not only that, we’re depleting our national strategic reserves,” Cao said.

Cao graduated from the prestigious Thomas Jefferson High School for Science and Technology in Alexandria, Virginia, before attending the US Naval Academy. He was commissioned as a special operations officer and went on to serve with SEAL teams and special forces in Iraq, Afghanistan and Somalia before retiring at the rank of captain, according to his Senate campaign biography.

Cao also earned a master’s degree in physics and had fellowships at the Massachusetts Institute of Technology and Harvard University.

Since becoming Navy Undersecretary, Cao has championed returning to duty service members that refused a Biden-era mandate to take the COVID-19 vaccine.