On May 25, 1925 a Junkers F.13 entered service as the first aircraft in Mongolian civil and military aviation. By 1935 Soviet aircraft were based in the country. In May 1937 the air force was renamed the Mongolian People's Republic Air Corps. During 1939–1945 the Soviets delivered Polikarpov I-15s, Polikarpov I-16s, Yak-9s and Ilyushin Il-2s. By 1966 the first SA-2 SAM units entered service, and the air force was renamed the Air Force of the Mongolian People's Republic. The MiG-15, UTI and MiG-17 the first combat jet aircraft in the Mongolian inventory, entered service in 1970 and by the mid-1970s was joined by MiG-21s, Mi-8s and Ka-26s.