These earlier posts may help show how to determine someone's military service status and whether or not they served within Vietnam:
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Dear Mr. Fuchs,
Thank you for posting your request on History Hub!
To verify his service, please begin by requesting a copy of his Official Military Personnel File (OMPF). OMPFs and individual medical reports for those who served in the U.S. Armed Forces during the Vietnam War are in the custody of NARA's National Personnel Records Center in St. Louis. In many cases where Army and Air Force personnel records were destroyed in the 1973 fire, proof of service can be provided from other records such as morning reports, payrolls, and military orders, and a certificate of military service will be issued. Navy and Marine Corps OMPFs were not affected by the fire. Please complete a GSA Standard Form 180 and mail it to NARA's National Personnel Records Center, (Military Personnel Records), 1 Archives Drive, St. Louis, MO 63138-1002. Certain information in the records is not available to the general public without the written consent of the veteran or his next of kin.
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