KYIV, Ukraine (AP) — One of Ukraine's largest drone strikes on Russia killed at least four people, including three near Moscow, and wounded a dozen others, local authorities said Sunday. Debris fell on Russia's largest airport without causing damage.

Ukrainian President Volodymyr Zelenskyy confirmed the drone strikes, saying that they were "entirely justified." Russia has repeatedly launched similar attacks on Ukraine's capital and other cities during the war, and an expert said that the strikes appeared to be retaliation for recent Russian attacks on Kyiv.

Russian drone strikes on Ukraine overnight wounded eight people, Ukrainian authorities said.

In Ukraine's strikes on Russia, a woman was killed after a drone hit her home in Khimki, a Russian city just northwest of Moscow, and two men died in the village of Pogorelki, which is 10 kilometers (6 miles) north of the capital, according to local Gov. Andrei Vorobyev.

Ukrainian drones had also damaged unspecified "infrastructure" and several high-rise buildings, Vorobyev said on social media.

One man was also killed after a drone struck a truck in the Belgorod region, which borders Ukraine, according to local authorities.

In Moscow itself, at least 12 people were wounded in the nighttime strike, mostly near the entrance to the city's oil refinery, mayor Sergei Sobyanin reported. Sobyanin reported that the "technology" of the refinery hadn't been damaged.

Russia's largest airport — Moscow's Sheremetyevo — said that drone debris had fallen on its grounds without causing damage or affecting flights.

Russian defenses shot down 81 drones headed for Moscow overnight, state agency Tass reported, citing Sobyanin, marking one of the largest attacks on the city since Russia launched a full-scale invasion of Ukraine on Feb. 24, 2022.

Russian air defenses destroyed 556 drones over Russia overnight, the country's defense ministry said Sunday morning. Shortly after midday local time, it reported that more than 1,000 drones had been shot down or jammed in the previous 24 hours.

Zelenskyy said that the drones had flown more than 500 kilometers (310 miles) from Ukrainian territory, and that Ukraine was "overcoming" Russian air defense systems concentrated in and around the capital.

"Our responses to Russia's prolongation of the war and attacks on our cities and communities are entirely justified. This time, Ukrainian long-distance sanctions have reached the Moscow region, and we are clearly telling the Russians: their state must end its war," Zelenskyy said.

Revenge for Russian attacks, expert says

Nigel Gould Davies, senior fellow for Russia and Eurasia at the International Institute for Strategic Studies, a London-based think tank, said that Ukraine's large-scale attack appeared to be "the retaliation or revenge that President Zelenskyy promised after the fierce attacks that Russia carried out on Kyiv."

Those strikes came immediately after the end of a brief ceasefire that allowed Russia to hold its annual Victory Day parade on May 9 commemorating the Soviet victory over Nazi Germany during World War II.

"It brings home the fact Ukraine has the capacity to strike at very significant scale at or around the Russian capital," taking the war home to Russians in a way that would be "most unwelcome" to the Kremlin, Gould Davies told The Associated Press.

"There is no ongoing peace process to disrupt. What (the attack) is more likely to do is add to the darkening cloud of anxiety over Russia which has developed palpably over the last three or four months," he said.

He cited a combination of factors, including Russia's recent battlefield setbacks, a deteriorating economic situation at home, and the Kremlin's intensifying crackdown on the internet, including in Moscow and Russia's second-largest city, St. Petersburg.

"The fact that Ukraine is reminding the Moscow population that it is vulnerable to these attacks is likely to intensify the mix of concerns now," Gould Davies said. "I see no prospect though, in the shorter term, that even these factors together will induce Russia to consider the compromises that will be necessary for peace negotiations."

Ukrainian drones are also flying deep into Russia to strike oil facilities, sending up plumes of smoke that can be seen from space and bringing toxic rain to tourist destinations on the Black Sea. The attacks are aimed at slashing Moscow's oil exports, a key source of funding for Russia's grinding invasion of Ukraine.

While their the economic impact is so far unclear — as the rise in oil prices from the Iran war, and a related easing of U.S. sanctions, have helped replenish the Kremlin's coffers — the range of the strikes and their environmental impact is bringing the war home to ordinary Russians far from the front lines.

8 wounded in Russian drone strikes on Ukraine

Russia attacked Ukraine with 287 drones overnight into Sunday, 279 of which were shot down or jammed, the Ukrainian air force reported.

The strikes wounded 8 people in Ukraine's central Dnipropetrovsk region: three in the regional capital of Dnipro, four in President Volodymyr Zelenskyy's hometown of Kryvyi Rih, and one in the district of Synelkove, Ukraine's state emergency service said.

Residential buildings were damaged in all three locations, the service said.