Turkey has paid Russia in full for the supply of S-400 air defense systems and the contract is closed, said Sergei Chemezov the head of Russian state corporation "Rostec" which is responsible for the sale to Ankara.

“We have fulfilled the contract in full, it is closed, which means that we have shipped and received all the funds,” Chemezov told reporters in Moscow today, Interfax reported.

The price of the S-400 systems is $ 2.5 billion, part of the contract was issued on credit, Chemezov had said earlier. The first contract provides an option to supply Turkey with an additional batch of S-400.

Chemezov stated that there are prospects for the development of military-technical cooperation with Ankara. "Of course, there are prospects. This contract was unique because it was implemented in a NATO country. We are negotiating with Turkish partners on other equipment, there are prospects," Chemezov said.

Turkey bought four divisions from Russia S-400. On October 23, 2019, Rosoboronexport announced that Russia fulfilled this contract ahead of schedule, supplying Turkey with all elements of the S-400 systems, including missiles.

Turkish President Recep Tayyip Erdogan confirmed on October 23 that Turkey has started testing the Russian-made system, brushing aside U.S. concerns. "(The tests) have been and are being conducted,” Erdogan told reporters. “The United States' stance absolutely does not concern us.”

“If we are not going to test these capabilities at our disposal, then what are we going to do?" he added.