Thus demonstrating the complete futility of the US drone programme. As I've said before, they might be effective against the shacks and shanty towns of Afghanistan, but the Chinese and the Russians will just send them back to destroy US aircraft carriers.
Neither Predator nor Reaper rely on GPS to get to their target.
And as for being able to spoof the signals between the pilot and the drone ... it would be easier to get onto an RAF base and steal a Typhoon.