WASHINGTON (AP) — The Pentagon announced Wednesday that the Navy’s top civilian official, Secretary of the Navy John Phelan, is leaving his job.

In a statement posted to social media, Pentagon spokesman Sean Parnell said Phelan was “departing the administration, effective immediately.”

Navy Undersecretary Hung Cao will become acting secretary of the Navy, Parnell said.

The sudden departure comes just a day after Phelan addressed a large crowd of sailors and industry professionals at the Navy’s annual conference in Washington, D.C., and spoke with reporters about his agenda.

Phelan’s departure also comes just weeks after Defense Secretary Pete Hegseth fired the Army’s top officer, Gen. Randy George. Hegseth also has fired several top generals, admirals and other defense leaders since taking office last year. As with many of those other firings, Pentagon officials did not offer a reason for Phelan's departure.

Phelan is leaving just as the U.S. Navy has imposed a blockade of Iranian ports and is targeting ships linked to Tehran around the world during a tenuous ceasefire in the Iran war.

Phelan had not served in the military or had a civilian leadership role in the service before President Donald Trump nominated him for secretary in late 2024.

Phelan was a major donor to Trump’s campaign and 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 non-profit that supported the defense of Ukraine and the defense of Taiwan.

The Associated Press could not immediately reach Phelan’s office for comment.

Cao ran a failed U.S. Senate bid in Virginia to try to unseat Democratic Sen. Tim Kaine in 2024. He had Trump’s endorsement in the crowded Republican primary.

Cao is a 25-year Navy veteran who served in combat zones. His 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 President Joe Biden.

“We are losing our country,” Cao said in video during the campaign, which blamed Biden for the criminal cases against Trump and showed footage of border crossings and store lootings. “You know it. But you also know that you can’t say it. We’re forced to say that wrong is right. We’re forced to lie.”