'Russia's diesel-electric submarine erupts in explosion'. Ukraine claims world's first underwater drone attack. Ukraine's State Security Service releases video. Video shows the submarine docked at Novorossiysk. Underwater drone was able to navigate a packed harbour? Russia, meanwhile, denies any damage caused by the attack. Russia: 'Not a single ship damaged as a result of sabotage'. Russia's diesel-electric submarines are extremely lethal. Russia's improved kilo-class subs carry Kalibr missiles

Ukraine's domestic security service, the SBU, said it struck a Russian submarine in the Black Sea port of Novorossiysk, Russia, disabling it, in a first attack of its kind. Russia acknowledged the attack but said no ships or submarines were damaged. Read more: https://cnn.it/4pFhm4R | CNN