if Maurice Ashley is not American then Hikaru Nakamura is also not American. both were born in other countries but moved with their family to America at a very young age and grew up there.
Nakamura is American by birth due to his mother being American. US nationality is automatic at birth via Jus sanguinis and/or Jus soli.
(And of course an immigrant to the United States can apply for citizenship after having resided in the United States for a certain number of years.)
Neat.