Törni joined the U.S. Army in 1954. The Lodge-Philbin Act was a special law that allowed non-citizens to join the army. He adopted the name Larry Thorne. While in the US Army, his friends were Finnish-American officers known as "Marttinen's Men." They helped Private Thorne join the Special Forces. While in the Special Forces, Thorne taught skiing, survival, mountaineering, and guerrilla tactics. In turn he attended airborne school. He advanced in rank and received a commission as a 2nd lieutenant in 1957. He was promoted to captain in 1960. From 1958 to 1962 he served in the 10th Special Forces Group in West Germany at Bad Tölz. While there he was second in command of a search and rescue mission in the Zagros mountains of Iran. The mission was very difficult and Thorne was praised because of its success.