In his early-days blitz, President Trump fired the first woman to ever lead a military service branch, signed an order to send active-duty U.S. troops to the border and said he was reinstating, with back pay, former service members who had refused to take Covid vaccinations, a breach of military health rules.

And a portrait of his former senior military adviser, whom Mr. Trump has accused of disloyalty, was swiftly taken down at the Pentagon.

Mr. Trump’s nominee for defense secretary, Pete Hegseth, said at his confirmation hearing last week that the president wanted a military “laser-focused on lethality, meritocracy, warfighting, accountability and readiness.”

It is not starting off that way.

Instead, the military is back where it has historically not wanted to be: in the middle of political and culture wars that could erode bipartisan support and, eventually, the public’s support for a military that is supposed to be apolitical.

The removal of the portrait of Gen. Mark A. Milley, the former chairman of the Joint Chiefs of Staff, from a hallway lined with portraits of others who have had the job, may be the least significant and yet most symbolically important of the White House’s decisions.