He continued his education at the Swedish Armed Forces Staff College, rising to the rank of captain and serving at various regiments.
He then joined the General Staff Corps, completing additional training in the United States and eventually becoming a lieutenant colonel.
Lahti attended the Swedish Armed Forces Staff College technical program from 1961 to 1963,[2] was promoted to captain in 1964, and then served at the Boden Artillery Regiment.
[3] After that, he worked as a teacher and course leader at the Swedish Armed Forces Staff College and was promoted to lieutenant colonel in 1972.
[8] Lahti served as head of the Equipment Department in the Army Staff from 1976 to 1978[9] and attended the Swedish National Defence College in 1977.
He was promoted to major general in 1983 and was appointed head of the main department for common technical matters at the Swedish Defence Materiel Administration, based at Karolinen [sv] in Karlstad.
Additionally, all Home Guard personnel were provided with the magazine Tidningen Hemvärnet [sv] at no cost to the individual.