Would guess from their general demeanour (racism lol) where they're from and what their motivations are. Then use that to decide - eg if I think they're muslim, I hit mecca; the sort of stereotypical patriotic Americans you get in 24, I hit Tel Aviv.
Well, obviously, that's what I would say in an online forum. No matter what their motivations, the people I kill are going to be innocent. So, obviously, I take the bullet.