Russia-Ukraine War Supported by Russia’s Defense Ministry said on Sunday that Ukrainian drones attacked airfields in five regions, and that several aircraft had caught fire. By Maria VarenikovaAnastasia Kuznietsova and Nataliya Vasilyeva Maria Varenikova reported from Kyiv, Ukraine, Anastasia Kuznietsova from Mantua, Italy and Nataliya Vasilyeva from Istanbul. Ukraine launched a large-scale coordinated assault on several air bases inside Russia on Sunday, the same day that a Russian strike on a Ukrainian military training base killed at least 12 soldiers. The dueling strikes came a day before both sides were expected to sit down for another round of cease-fire negotiations in Istanbul. Russia’s Defense Ministry said that Ukrainian drones had attacked airfields in five regions: Murmansk, Irkutsk, Ivanovo, Ryazan and Amur. Several aircraft caught fire in the Murmansk and Irkutsk regions, but the other attacks were repelled, the ministry said in a statement, adding that there were no casualties. Those details could not be independently verified, but the statement from the ministry came hours after an official in Ukraine’s security services, known as the S.B.U., said that a large-scale drone operation was underway. The official, who spoke on the condition of anonymity to discuss a sensitive intelligence operation, said that dozens of aircraft were damaged. It was not immediately possible to independently confirm that claim, but Russian military bloggers were quick to opine on what appeared to be a significant failure of defenses. “Today will later be called a black day for Russian long-range aviation,” read a post on the Telegram channel called Fighterbomber, which is believed to be run by Capt. Ilya Tumanov of the Russian Army. It added: “And the day is not over yet.” Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times. Thank you for your patience while we verify access. Already a subscriber? Log in. Want all of The Times? Subscribe.