ANKARA, April 3 (Xinhua) -- Russian President Vladimir Putin said Tuesday that Russia and Turkey agreed to bring forward the delivery of the S-400 missile defense systems to Turkey.

Speaking at a joint press conference with his Turkish counterpart Recep Tayyip Erdogan in Ankara, Putin said relations between the two countries are developing "step by step."

Erdogan said investment in Turkey's first nuclear power plant, which is being built by Russia's Rosatom at Akkuyu in the southern province of Mersin, will exceed 20 billion U.S. dollars.

Turkish and Russian delegations also met Tuesday for the Turkey-Russia High-Level Cooperation Council, which was attended by the presidents of the two countries and several ministers in order to enhance bilateral relations.