Defense Secretary Mattis’ acting replacement, Patrick Shanahan, is a former senior Boeing executive and an operations guy. He views his job as creating operational efficiencies, and carrying out what the top guy wants him to do. He thinks Trump is his top guy, not the American people, apparently. Shanahan has no military or foreign policy experience, and there is no evidence of strategic vision. He will make happen whatever Trump says.
That’s a terribly dangerous way to view the job.
For many obvious reasons, Trump is having trouble getting good people to work in his administration. One envisions a nearly empty White House peopled only by Javanka, Stephen Miller, and Mick Mulvaney, who wind up sharing all the jobs between them. Not only is Trump unlikely to attract an A-list candidate for DefSec, Trump actually likes people who follow his orders.
This lack of a permanent appointment at the top of the Defense Department isn’t going to turn out well.