SBU said a domestically produced Sub Sea Baby underwater drone struck and critically damaged a Kilo-class submarine in the port of Novorossiysk, releasing video that appears to show a large explosion and smoke column. Reuters and Dagens Nyheter reviewed the footage and port maps and said the clip appears to have been filmed where the SBU said, but both outlets and other international media could not independently verify when the video was recorded or that it shows a Russian submarine. Analysts warned the episode could mark a new chapter in naval drone warfare, and the SBU said the operation was carried out with the Naval Forces of Ukraine and the SBU's 13th Main Directorate while Moscow denied any damage.