The Sukhoi Su-24 (NATO reporting name: Fencer) is a supersonic, all-weather attack aircraft developed in the Soviet Union. This variable-sweep wing, twin-engined two-seater carried the USSR's first integrated digital navigation/attack system. It remains in service with former Soviet air forces and various air forces to which it was exported.
About 1,400 Su-24s were produced. Substantial numbers of ex-Soviet Su-24s remain in service with Azerbaijan, Belarus, Kazakhstan, Russia, Uzbekistan and Ukraine. Roughly 415 are currently operational with Russian forces, split 321 with the Russian Air Force and 94 with the Russian Navy.
Source: Wikipedia, "Sukhoi Su-24", available under the CC-BY-SA License.