the silo complex for the first time. In May 1960 the development of a new R-12 missile designated as R-12U was begun. The R-12U was designed to be used with both surface launchers and silos. The silo-launch complex of the R-12U missile comprised four launchers and was designated as "Dvina" (; )". The testing phase of the missile and the launch complex lasted from December 1961 through December 1963. The R-12 was also used during the development of the V-1000 anti-ballistic missile, serving as a target. During a series of tests two R-12s detonated their warheads in the upper atmosphere in order to test radar systems. A follow-on test planned to launch an R-12 from Kapustin Yar while two R-9s from Tyuratam would fly into the area, but only the R-12 launched successfully. Elimination The Intermediate-Range Nuclear Forces Treaty was signed in December 1987 and entered into force in June 1988. The fundamental purpose of the INF Treaty was to eliminate and ban US and Soviet ground-launched ballistic and cruise missiles, as well as associated support equipment, with ranges between 500 and 5500 kilometers. Elimination of R-12 and R-14 Chusovaya missiles and components took place at the Lesnaya Missile Elimination Facility. The last of the 149 Soviet R-12 missiles was eliminated at Lesnaya in May 1990. Space launcher variants Rockets with new booster In 1961, an upper stage using LOX and UDMH propellants was added to the R-12 to create the Kosmos 63S1 booster. Since there were no surface pads for the R-12, all launches took place from the Mayak silo at Kapustin Yar. However, as silos were not designed for repeated use, this arrangement proved impractical and necessitated their refurbishment after every few launches. The first two launch attempts of the 63S1 took place in October and December 1961 and both failed. On March 16, 1962, Kosmos 1, a navigation test satellite, was successfully orbited, marking the first Soviet space launch to be performed with a booster other than the R-7. Finally, a dedicated launch complex was constructed at Kapustin Yar and first used in December 1964. 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. In 1967, a second launch complex was opened at Plesetsk and from there on, 11K63 flights alternated between Kapustin Yar and Plesetsk, mostly