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 the Trump administration.No reason was given for the departure of Driscoll, who is a friend of Vice-President J.D. Vance, but tensions with Defence Secretary Pete Hegseth have been widely reported. It marks the latest in a series of shake-ups of top 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,” the statement said.The Pentagon referred questions to the US Army. The army has not immediately responded to an email seeking comment. A spokesman for Driscoll has not responded to a text message.Hegseth suddenly ousted the service’s top uniformed leader, General Randy George, in April, while the army’s commander in Europe and Africa, General Christopher Donahue, unexpectedly stepped down in June.General Christopher LaNeve, who has made a meteoric rise under Hegseth, took George’s place as the army’s acting chief of staff. Under LaNeve, the service is pulling the plug on a drone modernisation programme that Driscoll had heralded. An army unit based in Europe was building its own drones before LaNeve directed it to end its efforts and return to being a traditional infantry battalion, officials said this week.