Approximately 379 MiG-25P were converted to the more advanced MiG-25PDS (DS standing for field upgrade. NATO gave this variant the name Foxbat-E. The home base for the Soviet 146 Guards Fighter Regiment (Gv IAP) was located in Ukraine in 1950 as part of the 19th Defense Division that later became the 49th Air Defense Corp part of the 8th Air Defense Army. With the dissolution of the Soviet Union, the units and their MiG-25P and MiG-25PDS were taken over by Ukraine in 1992 and disbanded in 1993.