epa12149772 A handout photo made available by the Ukrainian Presidential Press Service shows Ukrainian President Volodymyr Zelensky (L) speaking with the Head of the Security Service (SSU) Vasyl Malyuk (R) during their meeting in Kyiv, Ukraine, 01 June 2025. Malyuk reported on the operation against Russian airbases. According to the SSU, seven billion US dollars is the estimated value of the Russian strategic aviation which was hit 01 June as a result of the SSU's special operation 'Pavutyna (Cobweb)'. About 34% of strategic cruise missile carriers at the main airfields of the Russian Federation were hit, the SSU claims. EPA-EFE/UKRAINE PRESIDENTIAL PRESS SERVICE / HANDOUT HANDOUT EDITORIAL USE ONLY/NO SALES 
By Tom Balmforth and Max Hunder
Ukraine's domestic security agency, the SBU, acknowledged that it carried out the attacks and said they caused considerable damage.
The sheds were loaded onto trucks that were driven to the perimeter of the air bases. The roof panels of the sheds were lifted off by a remotely-activated mechanism, allowing the drones to fly out and begin their attack, the official said.
The security official, who spoke on condition of anonymity, said strikes were conducted on Sunday on four air bases, and that 41 Russian warplanes were hit.
An SBU statement posted on the Telegram messaging app estimated the damage caused by the assaults at $7 billion.
"Thirty-four percent of strategic cruise missile carriers at the main airfields of the Russian Federation were hit," the SBU said on Telegram.
Unverified video and pictures posted on Russian social media showed Russian strategic bombers on fire at the Belaya air base in the Irkutsk region of Siberia.
Igor Kobzev, the regional governor, said there had been a drone attack on a military unit near the village of Sredny, which is near the Belaya base, though he did not specify what the target was. He said the drones had been launched from a truck.
The Irkutsk region attack was the first time a drone assault had been mounted by Ukraine so far from the front lines, which are more than 4,300 km (2,670 miles) away.
That is beyond the range of the long-range strike drones or ballistic missiles Ukraine has in its arsenal, so required a special scheme to get the drones close enough to their target.
Photographs shared with Reuters by the Ukrainian security official showed dozens of short-range quadrocopter drones piled up in an industrial facility. The official said these were the same devices used in the attack.
Other images shared by the official showed the wooden sheds with their metal roofing panels removed, and the drones sitting in the cavities between roof beams.
Separate video posted on Russian Telegram channels, which has not been verified by Reuters, appeared to show matching sheds on the back of a truck.
The roof panels can be seen lying on the ground next to the truck, and the video footage shows at least two drones rising out of the top of the sheds and flying off.
The Russian online media outlet that posted the video, Baza, said in a caption that it was filmed in the district near the Belaya air base.
The Irkutsk region air base hosts Tupolev Tu-22M supersonic long-range strategic bombers, a type of aircraft that has been used to launch missiles against targets in Ukraine.
The operation was code-named "Spider's Web", according to the Ukrainian security official, and was personally overseen by Ukrainian President Volodymyr Zelenskiy and Vasyl Maliuk, head of the SBU domestic intelligence agency.
If confirmed, the strikes would be the most damaging Ukrainian drone attack of the war, and would be a significant setback for Moscow.
The source shared video footage shot from a drone, saying it showed one of the strikes. The images showed several large aircraft, some of which appeared to be Tu-95 strategic bombers, on fire.
(Writing by Max Hunder and Christian Lowe; Editing by Bill Berkrot)