In the high-vaulted main hall of Union Station in Washington, DC, the sound of a drone attack interrupts the morning rush hour. A dozen people suddenly freeze in place. Some point up into the air. Others crouch with hands over their heads in a vain attempt at self-protection. The commuters on their way to and from the trains pause to look at the stationary figures. After a minute or so, the leaf-blower sound of the drone attack cuts off, and the figures crumple to the ground, crying out in pain. As the cries of the victims fade, two attendants cover the bodies with blood-stained sheets.