Well if it becomes a cat/mouse game, the drones could start shielding their electronics and employing backup navigation methods if GPS fails (think robotic-sext

Well if it becomes a cat/mouse game, the drones could start shielding their electronics and employing backup navigation methods if GPS fails (think robotic-sextant-style celestial navigation). Of course, a robotic sextant is not going to be as accurate as GPS, but I bet you could get within 100-200m of your destination.