The Mikoyan-Gurevich MiG-23 (Микоян и Гуревич МиГ-23; NATO reporting name: Flogger) is a variable-geometry fighter aircraft, designed by the Mikoyan-Gurevich design bureau in the Soviet Union. It is a third-generation jet fighter, alongside similar Soviet aircraft such as the Su-17 "Fitter". It was the first Soviet fighter to field a look-down/shoot-down radar, the RP-23 Sapfir, and one of the first to be armed with beyond-visual-range missiles. Production started in 1969 and reached large numbers with over 5,000 aircraft built, making it the most produced variable-sweep wing aircraft in history. The MiG-23 remains in limited service with some export customers. The basic design was also used as the basis for the Mikoyan MiG-27, a dedicated ground-attack variant. Among many minor changes, the MiG-27 replaced the MiG-23's nose-mounted radar system with an optical panel holding a laser designator and a TV camera. The MiG-23's predecessor, the MiG-21, was fast and agile, but limited in its operational capabilities by its primitive radar, short range, and limited weapons load (restricted in some aircraft to a pair of short-range R-3/K-13 (AA-2 "Atoll") air-to-air missiles). Work began on a replacement for the MiG-21 in the early 1960s. The new aircraft was required to have better performance and range than the MiG-21, while carrying more capable avionics and weapons including beyond-visual-range (BVR) missiles. A major design consideration was take-off and landing performance. The Soviet Air Force (VVS) demanded the new aircraft have a much shorter take-off run. Low-level speed and handling was also to be improved over the MiG-21. Manoeuvrability was not an urgent requirement. This led Mikoyan to consider two options: lift jets, to provide an additional lift component; and variable-geometry wings, which had been developed by TsAGI for both "clean-sheet" aircraft designs and adaptations of existing designs.