 Generally, Gorky built single-seaters for the Soviet forces.Moscow constructed single-seaters for export, and Tbilisi manufactured the twin-seaters both for export and the USSR, though there were exceptions.The MiG-21R and MiG-21bis for export and for the USSR were built in Gorky, 17 single-seaters were helmed in Tbilisi (MiG-21 and MiG-21F), the MiG-21MF was first constructed in Moscow and then Gorky, and the MiG-21U was built in Moscow as well as in Tbilisi.