WASHINGTON (AP) — US Army Secretary Dan Driscoll is stepping down after 18 months on the job, the White House said Monday, in the latest departure of a top military leader during President Donald Trump’s administration.

No reason was given for the departure of Driscoll, who is a friend of US Vice President JD Vance, but tensions with Defense Secretary Pete Hegseth have been widely reported. It marks the latest in a series of shakeups of the military leadership, with the Army especially seeing major upheaval.

“Secretary Driscoll has been highly effective in advancing President Trump’s agenda to Make America Strong Again at the Department of the Army by providing outstanding leadership during historic military operations, restoring an emphasis on readiness and lethality, assisting with negotiations between Russia and Ukraine, and more,” White House spokeswoman Anna Kelly said in a statement.

“The United States Army is more powerful than ever thanks to his work alongside the Commander-in-Chief and Secretary of War,” she added.

A US Army official, who was not authorized to comment publicly and spoke on condition of anonymity, said Driscoll spoke with Trump on the current state of the Army and submitted his resignation. The official did not provide additional details. The Pentagon referred questions to the Army. Driscoll’s resignation was reported earlier Monday by The Wall Street Journal.