Although a U.S. national who is a resident or citizen of a foreign country may be subject to compulsory military service in that country, service in the armed forces of a foreign state is a potentially expatriating act under INA section 349(a)(3) only if performed voluntarily and with the intention of relinquishing U.S. nationality: Absent voluntariness and intent to relinquish U.S. nationality, service in the armed forces of a foreign state generally would not be potentially expatriating act if the individual is not serving as an officer UNLESS the foreign military is engaged in hostilities with the United States.   

Federal statutes long in force prohibit certain aspects of foreign military service originating within the United States.  The current laws are set forth in Section 958-960 of Title 18 of the United States Code.  In Wiborg v. United States , 163 U.S. 632 (1896), the Supreme Court endorsed a lower court ruling that it was not a crime under U.S. law for an individual to go abroad for the purpose of enlisting in a foreign army; however, when someone has been recruited or hired in the United States, a violation may have occurred.  The prosecution of persons who have violated 18 U.S.C. 958-960 is the responsibility of the Department of Justice.

Although a person's service in the armed forces of a foreign state may not constitute a violation of U.S. law, as noted above, such action could serve as evidence of an intention to relinquish U.S. nationality under 349(a)(3) of the INA [8 U.S.C. 1481(a)(3)] if the individual enters voluntary service in the armed forces of a state engaged in hostilities against the United States  An individual who  requests a Certificate of Loss of U.S. Nationality under INA 349(a)(3) must clearly and credibly establish that by voluntarily serving in the armed forces of a foreign state, they intended to relinquish U.S. nationality.   Each case is considered on its own facts and under applicable law.

See also information flyers on related subject available via the Department of State, Bureau of Consular Affairs home page. These flyers include:

• Accepting, Serving in, or Performing Duties of a Position with the Government of a Foreign State – Immigration and Nationality Act (INA) Section 349(a)(4)