MOSCOW, Aug. 22 (Xinhuanet) -- Russian President Vladimir Putin praised the work of the Russian navy and air force Monday and stressed the need for a strong military to effectively defend a big country like his.

　　The results of the joint strategic air force and naval exercises last week showed "positive changes" are taking place in the armed forces, Putin told the pilots and sailors who took part in the war games at a meeting in the Black Sea resort of Sochi, the Itar-Tass news agency reported.

　　"What I saw (during the exercises) allows me to speak about serious positive dynamics," Putin said.

　　Putin flew on a missile-carrying, supersonic Tu-160 strategic bomber jet on Aug. 16 to witness missile launches and midair refueling as part of the maneuver.

　　Putin later boarded missile cruiser Pyotr Veliky to watch the Northern Fleet's exercises in the Barents Sea, during which submarine Yekaterinburg launched a ballistic missile from a subsurface position in the sea.

　　Only by constantly working to hone their skills can the army live up to the present day's needs, the Russian president said. "The country will have no future without the army and the navy," he said.

　　"Any country, especially a large one like Russia with big national interests, needs to be effectively defended," Putin said.