At least for the time being, the Department of Defense is being led by a former contractor with limited government and no active duty military experience. Patrick Shanahan, the former Boeing executive who was elevated to the Pentagon”s top job after the departure (or dismissal) of former Marine General Jim Mattis, has a reputation as a private sector problem solver.At Boeing, Shanahan led turnarounds of the 737 Max and 787 Dreamliner program, and earned a reputation of a detail-oriented senior executive.