Overnight Defense — Presented by Raytheon — First lady's office pushes for ouster of national security aide | Trump taps retired general as ambassador to Saudis | Mattis to visit border troops | Record number of female veterans to serve in Congress

Happy Tuesday and welcome to Overnight Defense. I'm Ellen Mitchell and here's your nightly guide to the latest developments at the Pentagon, on Capitol Hill and beyond. THE TOPLINE: First lady Melania Trump's office has...