Angola
The Soviets supplied the communist government of Angola with 12 Su-20Ms in 1982 or 1983, which formed the basis of the 15th FS. The squadron suffered a swift loss of at least six aircraft – most in mishaps - by 1985, and three more by 1988, and had only two aircraft left when it was reinforced with another Soviet batch of 14 Su-22M-4Ks and two Su-22UM-3Ks in 1989–1990 (incorporated into the 26th Air Regiment, based in Mocamedes). A third shipment from Slovakia in 1999-2000 consisted in 10 Su-22M-4s and one Su-22UM-3K.
These aircraft saw heavy use in the war against UNITA. Apart from the aforementioned losses (which can't be classified as mishaps or combat attrition), an Su-20M, serialled C510 was downed in 1987 and a more well-documented case occurred on 6 November 1994 when an Su-22 based at Catumbela was shot down by a SAM fired by UNITA during a raid over Huambo. The pilot managed to eject and flee naked after stripping off his flight suit.
Read more about this topic: Sukhoi Su-17, Operational History