By 1975 preliminary reports had reached the West of a considerbly modified version of the F-6, the MiG-19SF and PF built under licence in China. (Unlike the MiG-21, built in as small numbers as the Shenyang F-8, the earlier F-6 continued in production and proved useful by China and various export customers.)
The Shenyang complex of the Chinese aerospace industry has long been known for painstaking quality and attention to detail, but also for a lack of original design experience. It cannot have been easy to derive a largely new twin-engined fighter from the F-6, differing in such respects as generally increased size, a large nose radar and lateral engine inlets.
First announced in the West by US Defense Secretary Rumsfeld in 1976, when it was described as the Fantan-A fighter-bomber, the F-9 was originally powered by Tumansky RD-913 engines, each rated at 3250-kg (7164-1b) thrust with maximum afterburner.