I love the term ‘space alien’. I think that’s how aliens would like to be called.

Since the question of earthly citizenship comes first, i don’t think american citizenship would even be considered (de juris citizenship ((birthright citizenship)) applies only to humans i think, anyway, so alien would be comsidered an animal for the purposes of not filing paperwork on it)

Does Earth have de juris citizenship? For all species in general i don’t think anyone has written that it does, but i bet the UN woild support considering that Space Alien to be the first of its species native to Earth.

However, the alien species might not even have a concept themselves of de juris citizenship and may only care about bloodline.