From 1982 to April 1991, the Soviet Union successfully launched a total of 43 GLONASS-related satellites plus five test satellites. When the Soviet Union disintegrated on 25 December 1991, twelve GLONASS satellites in two planes were operational; enough to allow limited use of the system (to cover the entire territory of the Union, 18 satellites would have been necessary). The Russian Federation took over control of the constellation and continued its development. GLONASS became operational in the year 1993 with 12 satellites in 2 orbits at the height of 19,130 km. The United States GPS system has achieved full operation а year later. In December 1995, the GLONASS constellation was increased to 24 satellites. At present, there are a total of 27 satellites in orbit, and all are operational.