In recent months, however, the president has cooled on Mattis, in part because he’s come to believe his defense secretary looks down on him and slow-walks his policy directives, according to current and former administration officials.

The dynamic was exacerbated with Trump’s announcement in March that he had chosen John Bolton as national security adviser, a move Mattis opposed, and Mike Pompeo’s confirmation as secretary of state soon after.

The president is now more inclined to rely on his own instincts or the advice of Pompeo and Bolton, three people familiar with the matter said.