Surely Aran Bell is American, but how would that be meaningful if his training is POB-based, one of the foundational rather than eclectic classical styles/curriculums? Gillian Murphy, Tanaquil LeClercq, and Michelle DePrice received all of their dance education in the US, but they wouldn't qualify.
I feel this is the crux of the matter - whatever it is that makes an "American/US" Ballerina, in stylistic terms, has little to do with place of birth. Obviously training has a lot to do with one's aesthetic choices, but environment, and influence from choreographers and fellow company members can't be underestimated. As an example, Maria Kochetkova is no doubt sold to new audiences (think ABT) as "Bolshoi-trained", but she's developed into something decidedly un-Russian when seen in non-Petipa ballets. And that's coming from her years at SFB, working with current choreographers, and traveling the world doing endless galas. I almost find this more interesting: what turns a "foreign" dancer into an "American" dancer?
Enjoyed Kathleen O'Connell's rant very much. ;)