Work on improving the existing T-80 MBT begun as early as the mid-1970s with the design bureau in Leningrad. Here, developers were responsible for the production of the T-80 and started working on a joint project to further enhance the T-80's capabilities.In the early 1980s, the first prototypes were being built and after extensive testing and design tweaking, the new tank was considered ready for production. The resultant tank was accepted by the Soviet military under the designation T-80U. The T-80U received turret and upper frontal enhancements as part of its new construction along with being equipped with a second generation ERA protection system known as Kontakt-5. In contrast to the previous generation of dynamic protection, Kontakt-5 increased the tank's protection against HEAT and armour-piercing shells. The modifications also affected the armament of the tank - the T-80U is equipped with a new 1A45 fire control system and Reflex ICBM, which used more advanced 9M119 guided missiles. Subsequently, the tank was equipped with a new, more powerful GTD-1250 gas turbine engine which helped compensate for the increased weight of the vehicle and improved its dynamics. The T-80U had been factory produced in Leningrad in 1987, but in 1989, its production was moved to Omsk. Work on upgrading the T-80 was carried out in Kharkov, but there, they constructed their own vehicle equipped with a diesel engine, which was designated 'T-80UD'. The latter would evolve into further developed Ukrainian derivatives of the T-80. T-80Us served with the Soviet military until the collapse of the Soviet Union in the late 1980s and have since continued serving with the Union's successor states to this day. The vehicle also saw service abroad with some other countries as well, primarily with South Korea and 0Cyprus. Overall, around 700 T-80Us have been produced since 1985.