In an operation said to be 18 months in the planning, Ukraine conducted a devastating series of drone strikes against Russia air bases on Sunday.

Ukraine unleashed more than a hundred drones smuggled deep into Russia in what it called its most damaging attack yet.

Ukraine’s strikes on distant Russian airbases with drones smuggled into the country is believed to have destroyed several of Moscow’s long-range bombers.

Hours later came a report of another bridge collapse, also in western Russia, involving a freight train. By Ivan Nechepurenko and Caroline Houck A bridge overpass in western Russia collapsed late Saturday,

Explosions caused two bridges to collapse and derailed two trains in western Russia overnight, officials said Sunday, without saying what had caused the blasts. In one of the incidents, seven people were killed and dozens were injured.

Russia’s top investigative body is opening criminal probes into the collapses in Kursk and Bryansk. More than 70 people were injured, officials said.