Ukraine has carried out large-scale drone strikes against several air bases deep inside Russia, destroying multiple combat planes, according to the Ukrainian Security Service (SBU).

The operation, dubbed “Spiderweb,” comes on the eve of expected peace talks in Istanbul between Russia and Ukraine, and involved the most ambitious simultaneous strikes on Russian air bases carried out by Ukraine since the war began.

An SBU source said that Russian bombers were “burning en masse” at four air bases hundreds of miles apart, adding that drones had been launched from trucks inside Russia.

Ukraine planned the operation for more than a year and a half and used 117 drones to carry out the attacks, Ukrainian President Volodymyr Zelensky said in an address on Sunday night.

“The planning, organization, and all the details were perfectly prepared. It can be confidently said that this was an absolutely unique operation,” Zelensky said.

US Defense Secretary Pete Hegseth received regular updates as he traveled to Joint Base Andrews on Sunday but has not yet spoken to his Ukrainian counterparts, the official said.

The Department of Defense is continuing to assess the extent of the damage from the attacks and determine the details of the operation, the official added.

More than 40 aircraft were known to have been hit, according to the SBU source, including TU-95 and Tu-22M3 strategic bombers and one of Russia’s few remaining A-50 surveillance planes. According to the SBU, the operation caused an estimated $7 billion in damages and hit 34% of Russia’s strategic cruise missile carriers at its main air bases.

“We are doing everything to drive the enemy from our native land! We will strike them at sea, in the air, and on land. And if needed — we’ll reach them even from underground,” the SBU said in a statement.

The airfields targeted included Belaya in Irkutsk, some 4,500 kilometers (2,800 miles) from Ukraine’s border with Russia, and the Dyagilevo base in Ryazan in western Russia, about 520 kilometers (320 miles) from Ukraine, which is a training center for Russia’s strategic bomber force.

The Olenya base near Murmansk in the Arctic Circle, more than 2,000 kilometers (1,200 miles) from Ukraine, was also struck, according to the source, as well as the Ivanovo air base, more than 800 kilometers (500 miles) from Ukraine. Ivanovo is a base for Russian military transport aircraft.

The Russian Ministry of Defense confirmed Ukraine had targeted Russian airfields across five regions on Sunday, calling the drone strikes “terrorist attacks.”

The ministry said strikes were repelled in the Ivanovo, Ryazan and Amur regions but that “several pieces of aircraft” caught fire after attacks in the Murmansk and Irkutsk regions. It added that the fires had since been extinguished.

There were no casualties as a result of the attacks, the ministry continued, adding that “some participants in the terrorist attacks have been detained.”

The governor of Irkutsk region, Igor Kobziev, said that drones had been launched from a truck near the Belaya base.

Kobziev said on Telegram that the exact number of drones deployed had not been determined. Emergency and security services were at the site, he added.

SBU drones were targeting aircraft that bomb Ukrainian cities every night, the SBU source said.

One video supplied by the source purportedly shows the Belaya airfield in flames and the voice of the head of the SBU, Lt. Gen. Vasyl Malyuk, commenting on the situation. “How beautiful Belaya airfield looks now. Enemy’s strategic aircraft,” he says.

The SBU source said that the operation was “extremely complicated from a logistical point of view,” with the drones carried inside wooden mobile homes that had been carried into Russia on trucks.

“The drones were hidden under the roofs of the houses, which were already placed on trucks. At the right moment, the roofs were remotely opened, and the drones flew to hit Russian bombers.”

One video purportedly of one attack appears to show drones rising from a truck, as vehicles pass on a nearby highway. Another image shows the roof of the truck on the ground.

The source added that people involved were already back in Ukraine.

Ukraine’s operation followed a Russian attack overnight Saturday that involved 472 drones – Moscow’s largest drone attack since the war began. It came the same day as a Russian missile strike on a training site used by Ukrainian forces, killing at least 12 people and wounding more than 60 others. It also came soon after two bridges collapsed in Russia’s western regions bordering Ukraine in unclear circumstances.

This chain of events comes as Russia and Ukraine are set to return to peace negotiations on Monday. The talks, which will take place in Istanbul, have been strained by uncertainty. US President Donald Trump has expressed frustration around Russian President Vladimir Putin’s resistance to advancing the peace talks.

Putin proposed holding “direct talks” in Turkey earlier this month – but never showed up, despite Zelensky agreeing to meet. In the end, the two nations sent low-level delegations to negotiate instead.

A framework from the Ukrainian delegation lists key principles for the talks that include a full and unconditional ceasefire, an exchange of prisoners, and the release of hostages and return of abducted children.