i'm not backing up any of my statements, but i'm relatively certain that the US uses high altitude surveilance devices, or at least ones that are high enough to not really be noticed by ground troops

also, picking out encryption is a bit different - you actually have to be around the drone to know that they're there and you still won't know all they've seen. breaking an encryption means you see everything the drones have seen and you don't even have to know where it is.