Kyiv has destroyed more than 40 military aircraft in a drone attack deep in Russia, a Ukrainian security official said.
The attack on Sunday came as Russia pounded Ukraine with missiles and drones a day before the two sides meet for a new round of direct talks in Istanbul.
The official said the attack took more than a year and a half to execute and was personally supervised by Ukrainian President Volodymyr Zelensky.
The operation saw drones transported in containers carried by trucks deep into Russian territory, he said.
The drones reportedly hit 41 bombers stationed at several airfields, including the Belaya air base in the Russian region of Irkutsk, more than 2,500 miles from Ukraine.
It is the first time that a Ukrainian drone has been seen in the region, local governor Igor Kobzev said, stressing that it did not present a threat to civilians.
The attack was disclosed on the same day as Mr Zelensky said Ukraine will send a delegation to Istanbul for a new round of direct peace talks with Russia on Monday.
In a statement on Telegram, Mr Zelensky said that defence minister Rustem Umerov will lead the Ukrainian delegation.
“We are doing everything to protect our independence, our state and our people,” Mr Zelensky said.
Ukrainian officials had previously called on the Kremlin to provide a promised memorandum setting out its position on ending the war before the meeting takes place. Moscow had said it would share its memorandum during the talks.
Russia on Sunday launched the biggest number of drones – 472 – on Ukraine since the full-scale invasion in February 2022, Ukraine’s air force said.
Russian forces also launched seven missiles alongside the barrage of drones, said Yuriy Ignat, head of communications for the air force.
Earlier on Sunday, Ukraine’s army said at least 12 Ukrainian service members were killed and more than 60 were injured in a Russian missile strike on an army training unit.
The training unit is located to the rear of the 620-mile active front line, where Russian reconnaissance and strike drones are able to target.
Ukraine’s forces suffer from manpower shortages and take extra precautions to avoid mass gatherings as the skies across the front line are saturated with Russian drones looking for targets.
“If it is established that the actions or inaction of officials led to the death or injury of servicemen, those responsible will be held strictly accountable,” a Ukrainian ground forces statement said.
Russia’s Ministry of Defence said on Sunday that it had taken control of the village of Oleksiivka in Ukraine’s northern region of Sumy. Ukrainian authorities in Sumy ordered mandatory evacuations in 11 more settlements on Saturday as Russian forces make steady gains in the area.
Speaking on Saturday, Ukraine’s top army chief, Oleksandr Syrskyi, said that Russian forces were focusing their main offensive efforts on Pokrovsk, Toretsk and Lyman in the Donetsk region, as well as the Sumy border area.