Something that wasn't mentioned is command & control. 1st tier militaries will have satellite communications, and be able to operate their drones world-wide. 2

Something that wasn't mentioned is command & control. 1st tier militaries will have satellite communications, and be able to operate their drones world-wide. 2nd & 3rd tier militaries will have nearby ground-stations, with control capabilities limited to just-over-the-horizon. Again, control of the high-ground is key. With regard to PRECIPITOUS HEIGHTS, if you are beforehand with your adversary, you should occupy the raised and sunny spots, and there wait for him to come up.