Ukraine security service sources tell BBC bombers "are burning en masse" - as Russia confirms Kyiv's drone attack.

Retired U.S. military leaders reacted on Sunday after Ukraine carried out a large-scale drone attack on Russian military aircraft deep inside the country, with one quipping that Russian President Vladimir Putin is "having a very bad day.

Ukrainian President Volodymyr Zelenskyy said he was sending a Ukrainian delegation to Istanbul for another face-to-face with Russian representatives.

Ukrainians are already comparing it with other notable military successes since Russia's full-scale invasion, including the sinking of the flagship of Russia's Black Sea fleet, the Moskva, and the bombing of the Kerch Bridge, both in 2022, as well as a missile attack on Sevastopol harbour the following year.

The attack followed a night of bombardment, with Russia launching 472 drones, Ukraine’s air force said. Earlier Sunday, Ukraine’s army said a Russian missile strike on an army training unit killed at least 12 Ukrainian service members and injured 60.

Ukraine has carried out large-scale drone strikes against four airbases deep inside Russia, destroying multiple combat planes, according to a source in the Ukrainian Security Service (SBU).

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