[davchana]

To add more to your point, if one has unknowingly US citizenship (through parents at birth or something) && a local citizenship (where one is living, like India, Canada, UAE, anywhere), that host country is not going to give same protections as compared to somebody with "only" US citizen. For example , US citizen having Iranian Passport in Iran are simply Iranian citizens in Iran Government eyes. (Replace Iran with any country). US citizen working/visiting in Canada, but having no Canadian citizenship, can go ask US embassy in Canada for help.