I was playing the Red Hammer campaign the other day and in one mission which called on me to destroy some fuel and ammo dumps, a very peculiar thing happened.
I snuck into the first base and took out a few men without anyone noticing. Sneaking around the back of the buildings, I noticed 2 T72s which were unmanned as the tank crews were just standing around. I decided to kill them and steal a tank which I believed I had achieved successfully and was quite happy to go around running over everyone in the base. I stopped to look at all of the damage and whilst I was still, a single tank crew member that had survived jumped in the tank and issued commands to me. Bemused, I noticed a tank moving up beside me and thought the worst, went it happily went about it's way and was followed by another tank. A minute later a Russian squad that was dropped off by a transport chopper entered the base. It seems as though the AI would not fire on me because the commander in the tank was registered as friendly so they didn't show cause for alarm, even as I was running them over.
You can see it as a bug if you want or an exploit of the AI..I don't really mind as it made most of the mission very easy. (I went back and did it properly)