In a meeting last July about the new administration’s objectives in Afghanistan, President Trump turned to his national security advisers and suggested they arrange a series of lunches for him with enlisted military personnel who had served overseas.

“The president made an analogy to a restaurant that he goes to,” said a senior White House official who was there at the discussions, “and he said that the guys who owned it hired some big-name consultants, told them what to do, renovated it … and it basically was a flop. He said, ‘All they needed to do was ask the waiters.’ His point was, sometimes when you really want to know what to do, you don’t go to the senior guys with the high price tags, you ask the people who are closest to the problem.”