USSR / Successional Countries USSR (SOV)
The U-2 has been flying since the mid-1950s. Although it will celebrate half a century since its first take-off next year, it is not yet going to "retire". The reason is simple. Although obsolete in the age of satellites, the construction from the last century may seem obsolete, the truth remains that the aircraft is a reliable platform for many reconnaissance systems. It is much more operative and cheaper against satellites.
In 1955, the armament of tank units of the Soviet Army included anti-aircraft self-propelled gun ZSU-57-2 (Zenitnaya Samochodnaya Ustanovka). Even at a time when series production was just beginning, it was clear that a vehicle without radar, a fire control system and without ammunition with proximity lighters was hopelessly obsolete. Therefore, work on its modernization and replacement began the following year.