In 1985 the chief designer of the Russian radar manufacturer Phasotron Alexander Tolkatschew was exposed as a spy . When it was clear that he had given away over 60 films and 2000 pages of documentation on the MiG-29 and MiG-31 radars as well as A-50 AWACS and soviet IFF systems an immedeate programm for changes was initiated. The new vulnerability of the radar should be cleared in 1991/92 by the introduction of the 9-13 S with new algorithms in the radar computer. As the most important improvements these jets got a new radar, the N 019 m "Topaz", which had better resistance against jamming than the predecessor model. In addition for the first time two targets could be attacked simultaneously by the use of the active R 77 missile . The MiG 29 S was equipped with new improved IRSTS and better testing capabilities for the radar. Additionally it can carry the infrared R 27 T as well as the R 27ER and ET with a larger motor. The external weapons loadwas increased from 3000 kg to 4000 kg and th maximum AOA was increased to 28°. Die only 16 jets which were ordered by the Russian forces were ready for use in 1994. The remaining 34 machines were offered later as MiG 29 SE for export. As of 1993 some improvements were offered gradually. As of 1995 air refuelling and air-to-ground capability was offered. Most of these improvements were considerably late, however, and were only available for later export models (see MiG 29 SE/SM). The production of the R 77 got substantially delayed by the disintegration of the Soviet Union, since the production place had to be transferred from the Ukraine to Russia.