Navy Secretary John Phelan will leave the Trump administration “effective immediately,” the Pentagon announced Wednesday, marking the latest departure of a top defense official this year.

“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,” chief Pentagon spokesperson Sean Parnell said in a statement posted on X.

It was not immediately clear why Phelan will be departing his post. Parnell said that the new acting Secretary of the Navy will be Undersecretary Hung Cao.

Phelan’s departure comes amid the U.S.’ naval blockade of Iran. Trump has seized two ships in the strait, which Iran has called a violation of the precarious ceasefire between the two countries. White House press secretary Karoline Leavitt said on Fox News Wednesday that the seizure was not a violation because they were “international vessels,” and insisted the blockade has been “massively effective.”

Phelan’s departure also comes after Defense Secretary Pete Hegseth forced out the Army’s top officer and two other Army generals earlier this month.

Hegseth ousted the Army chief of Staff, Gen. Randy George. Parnell later confirmed George’s departure, saying the top officer would be “retiring from his position…effective immediately.”

Hegseth has removed multiple senior officials he believes are associated with previous administrations. George was senior military assistant to Defense Secretary Lloyd Austin, who served in former President Joe Biden’s cabinet. George’s firing was in part a result of a brewing turf war between Hegseth and Army Secretary Dan Driscoll.

Hegseth has fired numerous officials since starting his tenure in 2025.

Last year, he fired Air Force Lt. Gen. Jeffrey Kruse, who headed the Pentagon’s Defense Intelligence Agency, after an initial assessment by the agency found that U.S. strikes on Iranian nuclear facilities were not as extensive as President Donald Trump had indicated.

Hegseth also fired Navy Vice Adm. Shoshana Chatfield; Joint Chiefs Chairman CQ Brown Jr.; Air Force Gen. Timothy Haugh; Navy Adm. Lisa Franchetti; and head of the Coast Guard, Adm. Linda Fagan.

This is a developing story. Please check back for updates.