见：

http://travel.state.gov/law/citizenship/citizenship_778.html

“In light of the administrative premise discussed above, a person who:

1. is naturalized in a foreign country;
2. takes a routine oath of allegiance to a foreign state;
3. serves in the armed forces of a foreign state not engaged in hostilities with the United States, or
4. accepts non-policy level employment with a foreign government,

and in so doing wishes to retain U.S. citizenship need not submit prior to the commission of a potentially expatriating act a statement or evidence of his or her intent to retain U.S. citizenship since such an intent will be presumed. ”