Lord Plebian
Chieftain
Ships are a different matter. As far as I know, they can never be booted the hard way.
However, you are right that there is one fundamental difference between the AI and the human player here: when the AI gives you a hard boot order, you can't ignore it: it's either war, or your units get kicked out to some square outside their borders. The AI however can always chose to ignore your boot order and leave the units where they are without declaring war.![]()
I think the criteria for hard-booting ships is that they can only be hard-booted if they have military units inside. This happened to me the other day and I was surprised. I was playing archipelago and the Zulu declared war on me (look at all my not-surprise).

I too would be interested in seeing this. I've never seen them respond so indifferently to the hard boot.