ANKARA, Feb. 20 (Xinhua) -- Russia will deliver the first batch of S-400 air defense system to Turkey in July and the missile systems will be activated in October, a Turkish defense official said Wednesday.

"Delivery of the S-400 system will begin in July. And in October, the system will be active," said Ismail Demir, head of Turkish Undersecretariat for Defense Industries, in a televised interview.

"There are two systems, and the second system's calendar is shifted. There is no problem," he added.

Turkey needs more than two air defense systems and has been conducting talks over the purchase of Patriot surface-to-air missile (SAM) system from the United States as well, Demir explained.

However, Ankara "cannot the content and details of the U.S. offer," the Turkish official noted.

Turkish President Recep Tayyip Erdogan said on Friday that the United States cannot fulfill Ankara's two basic conditions for buying the Patriot: offering credit and joint production, local media reported.