The Yugoslav Air Force had nine squadrons of 130 Soviet-made MiG-21 interceptors for air defence. First produced in the late 1950s, the MiG-21 design was largely obsolete in 1990 and represented a potential weakness in Yugoslavia's air defence. However, the bulk of the MiG-21 fleet consisted mainly of the "bis" variant, the latest production MiG-21 model, and was armed with Soviet Vympel K-13 (NATO reporting name: AA-2 "Atoll"), air-to-air missiles and some more modern Molniya R-60 (NATO reporting name: AA-8 "Aphid") missiles as well as twin 23 mm cannons. By 1989, Yugoslavia started developing a new domestic multirole fighter called Novi Avion, which was supposed to replace the MiG-21 and J-21 Jastreb fleets entirely. The design of the new aircraft was influenced by both Mirage 2000 and Dassault Rafale fighter types and it was to enter service by the early 2000s. As an interim solution, a modernization package was planned for the MiG-21 and it is speculated that India's MiG-21 Bison upgrade was actually intended for Yugoslav aircraft. In 1987, Yugoslavia acquired 16 MiG-29s.