In 1961, an upper stage using LOX and UDMH propellants was added to the R-12 to create the Kosmos 63S1 booster.
An enhanced R-12 booster was flown in 1965-67 from the Dvina silo at Kapustin Yar on suborbital tests, eventually giving way to the 11K63, a modernized, improved launch vehicle.