KUBINKA /Moscow Region/, August 25. /TASS/. The signing of an additional contract on the shipment of the S-400 air defense systems to Turkey is expected before the end of this year, Rosoboronexport CEO Alexander Mikheyev told journalists at the Army-2021 forum Wednesday.

"[An additional S-400 contract] is expected shortly. We are working on it. And ‘shortly’ means this year, of course," Mikheyev specified.

Russia and Turkey signed a contract on the shipment of S-400 systems from Moscow to Ankara in 2017. Turkey has become the first NATO country to buy these systems.