That MR post also raises an interesting point of language. Out of 50,000 acknowledged private security personnel in Iraq, their trade group, the PSCAI (for Private Security Companies' Association in Iraq, a nice echo of the Supreme Council for the Islamic Revolution in Iraq or SCIRI) describes them as follows: 3,000+ Americans, 15,000+ third-country nationals (Colombians, etc), 25,000+ Iraqis, and 7,000+ "ex-pats". These latter are defined as being British and South African.
So as well as the old saw about "I am a freedom fighter, you are a guerrilla, he is a terrorist", we now have "I am an expatriate, you are an American, he is a third-country national, and they are Iraqis." TCN is a US defence/diplomatic/spook term from the Vietnam era meaning a citizen of an allied nation, but it's curious that the British are explicitly excluded - and even odder that South Africans, who are neutral, are lumped in with the British.
Mind you, expat probably is a nationality in a sense - the phrase seems to be used only by the Commonwealth, not by Americans, there being a great difference between a British ex-pat and an American expatriate. Attributes: declassé, taste for cold beer, profession usually something related to large construction projects, aviation or shipping, or the military, blokish, British, Australian, New Zealand or South African.