...For several nights, military personnel had reported a mysterious breach of restricted airspace over a stretch of land that has one of the largest concentrations of national-security facilities in the U.S. The first drone arrived shortly. Kelly, a career fighter pilot, estimated it was roughly 20 feet long and flying at more than 100 miles an hour, at an altitude of roughly 3,000 to 4,000 feet. Other drones followed, one by one, sounding in the distance like a parade of lawn mowers. The drones headed south, across Chesapeake Bay, toward Norfolk, Va., and over an area that includes the home...