In the era of the Cold War, the military planners on both sides of the Iron Curtain were well aware of the threat to their security from both bombers that could carry nuclear weapons and spyplanes. Thus it was deemed essential to have fast fighter aircraft which could intercept and destroy such incoming threats. The MiG-23 was developed to succeed the MiG-21 as the standard Soviet interceptor. It was a major advance on the earlier aircraft. Its swing-wing configuration was a generation on from its predecessor. Deliveries began in 1972 and more than 3,000 aircraft were built before production ended in 1986. As was the case with many Soviet types, the MiG-23 was widely exported to satellite or friendly countries.