The sixth set of the sophisticated S-400 missile defence system is expected to be delivered to Russia's Aerospace Force by the end of this year, the TASS news agency reported. 

The delivery of one more regimental set of the S-400 Triumph air defence missile system to an air defense unit of the Aerospace Forces in the Moscow region is planned to take place by the end of this year, TASS said, quoting a release from the Russian Defence Ministry. 

Four sets of the air defence system are currently on combat duty to defend the airspace of Moscow and the Central Industrial District, and another set has been delivered to the Aerospace Forces. 

The S-400 Triumf is a new generation anti-aircraft missile system. It is capable of hitting an airborne target at a distance of up to 400 km with medium- and long-range missiles.