KYIV, Ukraine — A Ukrainian drone attack has destroyed more than 40 Russian planes deep in Russia’s territory, Ukraine’s Security Service said Sunday, while Moscow pounded Ukraine with missiles and drones just hours before direct peace talks Monday in Istanbul.

A military official, who spoke with The Associated Press on condition of anonymity to disclose operational details, said the far-reaching Ukraine attack took more than a year and a half to execute and was personally supervised by Ukrainian President Volodymyr Zelenskyy,who said 117 drones were used.

The military source said it was an “extremely complex” operation, involving the smuggling of first-person view, or FPV, drones to Russia, where they were then placed in mobile wooden houses.

“Later, drones were hidden under the roofs of these houses while already placed on trucks. At the right moment, the roofs of the houses were remotely opened, and the drones flew to hit Russian bombers,” the source said.

Social media footage shared by Russian media appeared to show the drones rising from inside containers while other panels lay discarded on the road. One clip appeared to show men climbing onto a truck in an attempt to halt the drones.

The drones hit 41 planes stationed at military airfields on Sunday afternoon, including A-50, Tu-95 and Tu-22M aircraft, the official said. Moscow has used Tupolev Tu-95 and Tu-22 long-range bombers to launch missiles at Ukraine. A-50s coordinate targets and detect air defenses and guided missiles.

The Security Service of Ukraine said the operation had destroyed 34% of Russia’s fleet of air missile carriers with damages estimated at $7 billion.

Russia’s Defense Ministry in a statement confirmed the attacks, which damaged aircraft and sparked fires on air bases in the Irkutsk region, more than 2,500 miles from Ukraine, as well as the Murmansk region in the north, it said. Strikes were also repelled in the Amur region in Russia’s Far East and in the western regions of Ivanovo and Ryazan.

Also Sunday, Russia’s top investigative body said explosions had caused two bridges to collapse and derailed two trains in western Russia overnight. Russian officials did not say what caused the blasts and the word “explosions” was later removed from an Investigative Committee news release.

Russia on Sunday launched the most drones — 472 — on Ukraine since its full-scale invasion in February 2022, Ukraine’s air force said.