Without leaving American airspace, remotely piloted surveillance drones — outfitted with cameras that provide real-time video — fly along the Texas border searching U.S. territory for drug smugglers, illegal immigrants and potential terrorists. Does the U.S. government ever risk the international fallout of using the aircrafts' high-tech surveillance abilities to take a peek south of the border — or share what they see with Mexican counterparts fighting for their lives? The American public likely never will know.