A series of recent events has me again thinking about the security threats posed by unmanned aerial vehicles — commonly referred to as drones. On July 3, Greenpeace activists crashed a drone they had draped in a Superman costume into the exterior wall of a spent fuel rod storage building at a nuclear power facility in Bugey, France. Security officials indicated that Greenpeace initially had launched two drones, but police intercepted one. The "direct action" stunt was not intended to cause damage, but instead to draw attention to what Greenpeace claims is lax security at French nuclear facilities. On July 10, a drone bearing two hand grenades crashed outside the home of Gerardo Manuel Sosa Olachea, the secretary of public security of Baja California state.