Interfere with the navigation system and you capture it. Works on drones and missiles and, are you ready, UFOs!
Here is an excellent description of the vulnerabilities of the US Drone program. Although packed with amazing combinations of electronics, satellite communications and navigation, imaging, and flight technologies, their vulnerabilities are the transmission of video images and the navigation system. First thing to be 'broken' were the video downloads. But the real weak point as this article in the Christian Science Monitor points out, is the GPS based Navigation system. A satellite signal, actually several signals combined, let the drone know where it is to within a few feet.
More drone wackyness. ;-) To read more, click here.