SOCHI, May 3. /TASS/. The deliveries of Russia’s advanced S-400 surface-to-air missile systems to Turkey were discussed at a meeting of Russian and Turkish Presidents Vladimir Putin and Tayyip Erdogan, Kremlin spokesman Dmitry Peskov said on Wednesday.

"This theme was touched upon, like other issues related to military and technical cooperation," Peskov said.

"Military and technical cooperation was discussed in a positive tone," the Kremlin spokesman said.

Russia and Turkey have been negotiating the deliveries of S-400 air defense missile systems since last year’s winter but both sides have not announced anything specific so far. They have only stated that the talks are proceeding positively and have entered their final phase but have not yet reached the stage of signing a contract.

In late April, Turkish Defense Minister Fikri Isik said that "a joint decision on forthcoming steps towards the acquisition of the Russian antiaircraft missile system" might be made following the negotiations between Putin and Erdogan.