8 C.F.R. § 343.1
A person who lost citizenship of the United States incidental to service in one of the allied armies during World War I or II, or by voting in a political election in a country not at war with the United States during World War II, and who was naturalized under the provisions of section 323 of the Nationality Act of 1940, as amended, or a person who, before January 13, 1941, resumed United States citizenship under the twelfth subdivision of section 4 of the act of June 29, 1906, may obtain a certificate evidencing such citizenship by making application in accordance with USCIS instructions. The applicant shall be required to appear in person before an assigned officer for interrogation under oath or affirmation upon the application. When the application is approved, a certificate of naturalization or repatriation shall be issued and delivered in person, in the United States only, upon the applicant's signed receipt therefor. If the application is denied, the applicant shall be notified of the reasons therefor and his right to appeal in accordance with the provisions of part 103 of this chapter.
8 C.F.R. §343.1