Americans are nationals and citizens of the United States of America. Although nationals and citizens make up the majority of Americans, some dual citizens, expatriates, and permanent residents may also claim American nationality. The United States is home to people of many different ethnic origins. As a result, American culture and law do not equate nationality with race or ethnicity, but with citizenship and permanent allegiance.
Which is a shame because the movie had an excellent chance to make a statement had it been willing to go off the rails a little bit (pun intended) and put some shading on these characters.