There are some unofficial document said F-5 of the Royal Thai Air Force has few dogfight with Mig-21of the Vietnam (VPAF) , at the border with Thailand -campuchia
(While MIG-21 to destroy the Khmer Rouge)
During this time, the VPAF mix of American and Russian aircraft:mig-21,F-5,mi-8,uh-1,a-37 .....