Russia launched an intense missile and drone barrage at the Ukrainian capital Kyiv in the early hours of Friday, killing at least six people, Ukrainian officials said, as powerful explosions reverberated across the country.

The attack on Friday, which killed at least four people nationwide, came two days after Russia vowed retaliation for an audacious drone assault on its strategic bomber bases.

Ukraine said its “Operation Spiderweb” attacked Russian warplanes worth hundreds of millions of dollars, utilizing drones that each cost under $1,000 and were launched from wooden containers carried on trucks.

Ukraine launched a stealthy and significant attack on Russia last weekend. Experts say it’s going to change modern warfare, but the U.S. isn’t prepared

Satellite imagery of a Russian air base taken shortly after Ukraine carried out a drone attack shows several strategic bombers were destroyed.

Ukraine says Russia launched hundreds of drones and dozens of missiles across the country in an overnight bombardment. It comes after the Kremlin had warned of retaliation against Kyiv for it's attack on Russia's strategic bomber aircraft.

At least five people were killed, including a child, and more than two dozen injured after Russian forces launched more than 100 drones, guided bombs and missiles at regions all across Ukraine overnight.

Ukraine on June 1 launched 117 individually-operated drones at four airbases across Russia, officials said, in an operation codenamed "Spiderweb".

Russian forces on Wednesday advanced further into Ukraine's northern region of Sumy, threatening the regional capital after taking more than 150 square km (58 sq miles) of the area in less than two weeks,

Neither Russia nor Ukraine has a clear path to victory. The Ukrainian drone attack last week and the Russian air raids on Friday don't change that.