Russia has bombarded Ukraine with the largest attack of the conflict, launching 479 drones overnight in a bold offensive, the Ukrainian air force said.

Russia launched a massive attack on Ukraine's Kharkiv, killing four and injuring dozens. President Zelenskyy condemned the violence and appealed for urgent air defense assistance.

Ukraine said its drones hit a Russian research and production facility that supplies components for missiles, as Russia unleashed a fresh barrage of air attacks overnight.

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 massive drone strike deep into Russia, hitting airbases and destroying over 40 bombers in its longest-range operation since the war began, according to officials.

Ukrainian President Volodymyr Zelenskyy said he was sending a Ukrainian delegation to Istanbul for another face-to-face with Russian representatives.

Ukraine says that a large Russian drone-and-missile attack has targeted the city of Kharkiv, killing at least three people and injuring 21.

Technological advances have given threadbare militaries and rebel fighters the ability to strike stunning blows against far stronger forces.