Turkish President Recep Tayyip Erdogan says he's made clear to U.S. President Joe Biden that Ankara's position on its S-400 missile systems remains unchanged, Sputnik News reports.

"I told Biden: Do not expect Turkey to take any new steps in relation to the F-35 or the S-400. Because we already did our part on the F-35. We asked you for the Patriot air defense system, but you did not give it to us. On the contrary, you even took away those that were stationed at our bases. What could we do? We solved this issue on our own," Erdogan said, speaking to reporters in Baku, Azerbaijan, his remarks cited by Sputnik Turkey.

Turkey and Russia penned a $2.5 billion deal in late 2017 on the delivery of four S-400 mobile air and missile defense batteries. Deliveries of the system began in 2019. Turkey has since indicated that it would like to purchase more S-400s.

The Turkish president confirmed to reporters that Biden would like to pay a visit to Turkey, and noted that amid the imminent U.S. and NATO withdrawal from Afghanistan, Ankara is prepared to take on "much more responsibility there."

He added that Turkey plans to discuss the subject of defense industry cooperation with its US ally in greater detail. "In the future negotiation process, the heads of the foreign ministry, the ministry of defense and the defense industry will be involved," Erdogan indicated.

Erdogan arrived in Azerbaijan for an official state visit on Tuesday, June 15.