Overnight Defense: Nauert tapped for UN envoy | Trump teases changes to Joint Chiefs of Staff | Trump knocks Tillerson as 'dumb as a rock' | Scathing report details Air Force failures before Texas shooting

Happy Friday and welcome to Overnight Defense. We're Rebecca Kheel and Ellen Mitchell, and here's your nightly guide to the latest developments at the Pentagon, on Capitol Hill and beyond. CLICK HERE to subscribe ...