MOSCOW, Aug. 27 (Xinhua) -- Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan said Tuesday that the two countries are ready to expand cooperation in the military sphere.

"We have used the opportunity of Mr. Erdogan's visit to discuss promising joint projects not only in aviation but also in other sectors of military-technical cooperation," Putin said at a press conference after their talks on the sidelines of the International Aviation and Space Salon, also known as MAKS.

Russia is ready to offer flights on Su-30SM fighters to Turkish pilots, Putin said, adding that he and Erdogan also discussed "cooperation on Su-35 and possible work on new Su-57" jets, but did not provide details.

Russia began on Tuesday the delivery of a second batch of S-400 air defense missile systems to Turkey, Putin said.

He said Russia has demonstrated new weapons and new radio-electronic warfare systems to Turkey and there are many possibilities.

"In my opinion there have been many things that aroused the interest of our Turkish colleagues, not only from the point of view of purchase but also from the point of view of joint production," Putin said.

Erdogan said that Turkey is willing to expand cooperation with Russia in various sectors of the defense industry, including warplanes and missiles.

Earlier on Tuesday, Putin and Erdogan talked with the Russian crew on the International Space Station via a teleconference during their visit to the MAKS-2019 exhibition that opened in a suburb of Moscow.