The move is a departure from past practice and has raised worries that it could lead to the politicization of the military’s top ranks.

© Haiyun Jiang for The New York Times

Suspicions about leaks and a mistrust of senior military officers have defined much of the defense secretary’s first six months on the job.

© Haiyun Jiang/The New York Times

A former senior U.S. official said it was “shortsighted” to consolidate the department’s well-respected intelligence arm.

© Nicole Tung for The New York Times