Russia and Turkey have signed a contract to deliver a second regiment of S-400 air defense systems to Turkey, the Russian state arms exporter Rosoboronexport said Sunday.

Rosoboronexport Director General Alexander Mikheev did not disclose further details when speaking to RIA Novosti news agency.

In 2017, Russia and Turkey finalized a deal worth about 2.5 billion U.S. dollars to supply Ankara with S-400 systems, and delivery was completed in 2019.

Turkey is the first member of the North Atlantic Treaty Organization to purchase such air defense missile system from Russia.

The S-400 missile system is considered the most advanced of its kind in Russia, capable of destroying targets at a distance of up to 400 kilometers and a height of up to 30 kilometers.