Defense Secretary Pete Hegseth on Thursday fired the Army’s top officer, Gen. Randy George, a move that is prompting concerns about the politicization of America’s military, particularly during a U.S. war in the Middle East.

General George became the latest of more than a dozen high-ranking officers in the military dismissed in President Donald Trump’s second term. Two other generals, including the Army’s top chaplain, were also fired Thursday.

In a social media post, Defense Department spokesman Sean Parnell thanked Mr. George for his “decades of service’’ and said that the general’s retirement would be effective immediately.…