'Huge breach of defences': Ukraine claims to have inflicted damage worth $2bn with drone attack deep inside Russia
More details now from Deborah Haynes, security and defence editor and Azad Safarov, Ukraine producer, on the special operation - codenamed "Web" - launched by Ukraine to target Russian bombers.
Ukraine is conducting a "large-scale" drone operation against the Russian air force, hitting more than 40 bomber aircraft across four bases deep inside Russia, security sources have said.
It appears to be the most significant operation of its kind since the start of Vladimir Putin's war in Ukraine more than three years ago, and is a huge breach of Russia's national defences.
A Ukrainian government source said that the drones were launched inside Russia.
One of the targets – the Belaya airfield – is more than 2,500 miles from the Ukrainian border.
Videos shared with Sky News by Ukraine's SBU Security Service purport to show a line of Russian strategic bombers with smoke billowing out of them.
"Enemy strategic bombers are massively burning in Russia - this is the result of a special SBU operation," a security source said.
"Right now, the Security Service of Ukraine is conducting a large-scale special operation to destroy enemy bombers in the rear of Russia.
"The SBU drones are targeting aircraft that bomb Ukrainian cities every night. So far, more than 40 planes have been hit, including A-50, Tu-95 and Tu-22 M3."
At least one of the videos is purportedly of the Belaya airfield.
A voice can be heard saying in Ukrainian: "This is how nice looking now airport Belaya, strategic enemy aviation."
The codename for the Ukrainian operation is "Web".
Sources claimed to have inflicted more than $2bn (£1.4bn) worth of damage on the Russian air force.
"We are waiting for the details. And we hope that the number of hit aircraft will increase!" one source said.
The other Russian airbases targeted by Ukraine were: Diagilevo, Olenya and Ivanovo airfields.