Almost 600 Ukrainian drones targeted various locations in Russia overnight, killing three people in the Moscow region and one in the Belgorod region, Russian authorities said on Sunday.

The attacks come after Ukrainian President Volodymyr Zelenskyy vowed on Friday to launch retaliatory strikes, a day after a Russian assault on Kyiv killed 24 people and injured around 50 more.

What has Russia said about the Ukrainian attacks?

According to local Governor Andrei Vorobyev, a drone attack killed a woman in her home in Khimki, just northwest of Moscow, while two men were killed in the village of Pogoreliki, 10 km (6 miles) north of the Russian capital.

The mayor of Moscow city, Sergei Sobyanin, said strikes there had wounded at least 12 people, most of them construction workers at a job site near an oil and gas refinery.

He said, however, that production at the refinery had not been disrupted.

Local authorities in the Belgorod region bordering Ukraine said one man there was also killed when a drone struck a truck. 

Russia's Defense Ministry said air defenses shot down 556 drones across the country overnight, with another 30 drones intercepted after dawn.

Russian state news agency TASS said that 81 of those drones were headed for Moscow overnight, making the attack one of the largest on the Russian capital since Moscow launched its full-scale invasion of Ukraine on February 24, 2022.

Attacks on Russia 'justified' — Zelenskyy

Russia, which has hit its neighbor with relentless ground and air attacks since it began its unprovoked full-scale invasion, sent 287 drones over Ukraine overnight to Sunday, 279 of which were shot down or jammed, the Ukrainian air force reported.

Ukrainian officials said the strikes injured eight people in Ukraine's central Dnipropetrovsk region, three in the regional capital of Dnipro, four in the town of Kryvyi Rih and one in the district of Synelkove.

President Volodymyr Zelenskyy called Ukraine's own attacks on Russia, and particularly on its capital region, "entirely justified" in view of the continued Russian aggression.

"Our responses to Russia's prolongation ​of the war and ​its attacks on ​our ‌cities and communities are entirely justified," he ‌said on X.

"The ‌distance from ​Ukraine’s state border is over 500 km. The ​concentration of Russian air defense ⁠in ​the Moscow ​region is the highest. ​But we ‌are overcoming it," he ​said.

"We ⁠are clearly telling the Russians: Their ⁠state ​must end its war," he added.

Diplomacy in the Ukraine conflict at a standstill

The attacks come as diplomatic efforts to end the conflict remain at standstill.

Among other things, Kyiv continues to reject the maximalist demands made by Moscow for territory in the eastern Donbas region, saying that fulfilling them would be a quasi reward for Russia's illegitimate military actions.

Attempts by the US in the past months to bring both sides to the negotiating table have also apparently stalled as Washington remains focused on itswar against Iran.

Edited by: Dmytro Hubenko