Anthony, it's not like that with military. GPS is for delivery (guidance) and fusing (detonation) but never used alone as it is jammable. Cartography is the big issue with GPS, as you say. Cartography can be a long way out -- in my personal experience hundreds of metres, quite far enough to kill you. The real danger is that it seems to be so accurate while it is miles out. If only GPS could shrug and say "not sure", but that isn't built into the system.