Those of you that want to know if the computer will use troops to invade you I at least know that they do load troops into transports. I captured an enemy troop transport in one game using the intelligence operation. It only had 6 troops on it but I then used it to capture two of the enemy planets and gave myself a nice foothold in the system
.
I haven't seen the AI actually using the troop transports but that is probably because I usually take the fight to their systems so they don't get much ofa chance to fight in my teritory. My guess is that if I just waited and didn't attack them first maybe made treaties with all of them till they turned on me that could happen.