According to the Rosoboronexport's director general, the contract for the delivery of Russian S-400 air defense missile systems to Turkey has been signed, but has not yet entered into force.

The contract for the delivery of Russian S-400 air defense missile systems to Turkey has been signed, but has not yet entered into force, Russian state arms exporter Rosoboronexport's Director General Alexander Mikheev told Sputnik on Tuesday.

"The contract for the delivery of Russian S-400 air defense missile systems is close to signing, but has not been signed yet and, accordingly, has not yet entered into force," Mikheev said at the Army-2017 forum.

The Russian-Turkish talks on the delivery of S-400 systems have been taking place since 2016. In March, Sergei Chemezov, CEO of Russia’s Rostec Corporation, said Ankara was ready to buy the systems with a loan granted by Moscow. 

On July 18, Chemezov said the technical issues of the contract for the supply of the S-400 systems to Turkey had been resolved, with only administrative ones remaining.

Later on, Turkish presidential spokesman Ibrahim Kalin said only a few nominal issues are left to be cleared up in a generally formalized contract on the delivery of Russia's S-400s to Turkey.

Turkish President Recep Tayyip Erdogan in late July announced that Ankara and Moscow had signed a document on supplies of the S-400 Triumf systems.