https://en.wikipedia.org/wiki/Lauri_T%C3%B6rniLauri Allan Törni (28 May 1919 – 18 October 1965), later known as Larry Alan Thorne, was a Finnish-born soldier who fought under three flags: as a Finnish Army officer in the Winter War and the Continuation War ultimately gaining a rank of captain; as a Waffen-SS captain (under the alias Larry Laine) of the Finnish Volunteer Battalion of the Waffen-SS when he fought the Red Army on the Eastern Front in World War II; and as a United States Army Major (under the alias "Larry Thorne") when he served in the U.S. Army Special Forces in the Vietnam War.
https://norwalkctheroes.org/2020/07/23/major-larry-alan-thorne-u-s-army-finland-germany/