Battery life. If necessary, humans can stay active for a long time. Robots can't. If it dies, you either manually get the robot, or leave it for the enemy. The more processing and sensors on a platform, the sooner it dies. An almighty AI will likely require an almighty amount of power.
Cameras. Humans swiftly adapt to lighting, can deal with very dark and very bright conditions, have an amazing field of view, can accurately track tiny objects very far away, and very quickly refocus and swivel our eyes and head. You'll have a lot of trouble finding cameras+mounts that meet all of these criteria that aren't a giant bullseye. It's more likely that you need to tailor your sensors for particular situations. What we see as a person at 80 meters might be a few pixels if the camera is zoomed out. If you zoom in, you'll see the enemy, but not your surroundings.
Communications. Quickly transmitting binary data at the ground level is a very open-ended problem.
Positioning. GPS doesn't work within buildings. Some of your platform power will be allocated to dealing with this fact.
[This is based upon my experience of trying to keep up with my son playing Halo rather than Ender's Game]
The more we try to computerize warfare and make it antiseptic, the easier it becomes for us to ignore that fact. Admittedly this is effective - when we don't feel the pain of war we are able to inflict more of it - but fundamentally I think it is wrong.
I believe kirk ended the show with destroying their computers and giving them a moral lecture on the horrors of war...
Anyway, your post reminded me of it.
Ultimately war will exist entirely online, because all of the most important things will be in cyberspace. Once reality as we know it has been reduced to simply hosting the processors that host our made up worlds, then maybe we can permanently keep war where it should be, inside video games.
This was the plot of a Star Trek episode, where the losers had to docilely line up to be incinerated when the computer determined that they had been "killed" in the simulated battles. It was all much less messy that way.
Of course, when Kirk destroyed the incinerators (or was it the master computer?) they had to decide whether to fight the messy way, or maybe just not fight at all.
Why would the other side agree to use chess to determine the outcome? More to the point - if they would, why would you?
War is a decision-making process, but one of the constraints is that both sides aren't willing to give in absent significant costs.
The interview is here:
http://www.scotsman.com/spectrum/Interview-Andy-McNab-soldie...
The bit about the brain scans is on page 5:
http://www.scotsman.com/spectrum/Interview-Andy-McNab-soldie...
