Good argumentation, Blooz. Seems you've been studying your share in human behavior.
In a two country situation I would like to add one more aspect: Racism. People on the opposite side would be considered as "them", which soon would become a synonym to "axis of evil" or any other national arch enemy. Sooner or later we would have a virtual WW3 running on this board, recruiting people to the "right" side and flaming those on the "wrong" or even "evil" side. With three countries having similar planesets this is just a game instead of a political battlefield.