Washington is pouring energy into a sweeping “Golden Dome” missile shield to detect and defeat the most catastrophic threats to the U.S. homeland. But in March, a far cheaper—and arguably more revealing—test of American defense played out at ground level, one with alarming consequences for the homeland. Waves of unauthorized drones flew over Barksdale Air Force Base in Louisiana, one of the most strategically important U.S. military installations. Barksdale sits at the intersection of nuclear