The purchase of Russian S-400 anti-aircraft missile systems should not affect US-Turkey relations, Turkish President Recep Tayyip Erdogan said, Trend reports citing Turkish media.

Erdogan noted that S-400 air defense systems are in great demand in Turkey and the US understands this very well.

"There are other NATO member countries that also have Russian air defense systems, but when it comes to Turkey, for some reasons, the US reacts negatively," he said.

Russian S-400 anti-aircraft missile systems will be installed in Turkey in December 2019. After the installation of all S-400 components, Turkey’s anti-aircraft missile system will be ready for their use in April 2020.

On Sept. 12, Turkish Foreign Minister Mevlut Cavusoglu said that the Russian S-400 air defense systems will be used in Turkey in 2020.

Turkey will not transfer the S-400 systems to anyone and will not use them in other countries, Cavusoglu added.

Turkish Minister of National Defense Hulusi Akar said on July 12 that the first batch of S-400 anti-aircraft missile system components is being sent to Turkey.

NATO previously expressed concern over the reports of the delivery of S-400 missile systems to Turkey.

It was stated earlier that the Turkish Ministry of National Defense will determine the exact location of the Russian S-400 missile systems after acquiring the first S-400 shipment.