On February 4, Russia’s Central Military District reported the successful conclusion of air defense exercises in the Urals, Siberia, and Volga region. In the drills, S-300 and S-400 systems repelled notional aerial targets represented by MiG-31 fighters and Army Mi-8 helicopters. The S-300 and S-400 are a family of Russian air defense systems which entered service in 1978 and 2007, respectively.