Ukraine launched hundreds of drones Thursday targeting more than a dozen Russian regions, striking an oil refinery in Moscow and sending plumes of black smoke over the city.
Officials said the strike marked the second time in a week that a major Moscow refinery was hit and that the assault disrupted hundreds of flights at the capital's airports.
Officials called the operation one of Ukraine's biggest drone attacks since Russia's full-scale invasion over four years ago.
Some Ukrainian officials framed the attacks as revenge or as strikes on a historic monastery that drew global condemnation.
Russia's Ministry of Defense said it shot down at least 555 Ukrainian drones, and Moscow Mayor Sergei Sobyanin said about 180 of those were shot down as they approached Moscow.
Ukraine laid claim to the aerial attack; Ukrainian President Volodymyr Zelenskyy said on social media: "This is a fully justified response to Russian attacks on our cities and communities, and another important result of our warriors' work against facilities that sustain Russia’s war machine." He added that Ukraine's partners "have noted the precision and effectiveness of our mid-range strikes and long-range sanctions."
Video showed a drone flying into a plume of smoke over the Kapotnya refinery in the southeast of Moscow, about 10 miles from the Kremlin, as air defense rockets were fired and the facility was seen engulfed in flames.
The Moscow public prosecutor’s office said "several" districts in the city were attacked and reported damage to apartment buildings and casualties but did not detail them.
The General Staff of the Armed Forces of Ukraine said Russia fired at least seven ballistic missiles and 239 drones at Ukraine overnight; Ukraine said its defenses shot down or otherwise destroyed at least 216 drones or missiles.
Russia's Department of Defense said it launched in response a drone-and-missile attack against "fuel and energy facilities used by the Ukrainian Armed Forces."
Russia's transportation ministry said the capital's major airports went into temporary shutdown Thursday morning "to ensure flight safety," and Russia's aviation authority announced restrictions on flights by light private aircraft and drones the day before.
Kyiv has been striking oil facilities deep inside Russia after a leap in drone capabilities, an intensifying campaign that Kyiv's allies say has given the country "new momentum" and that has led to widespread damage to energy infrastructure and a fuel crisis centered in occupied Crimea; successful attacks on Moscow remain rare because the capital is protected by layers of air defense.
The attack came hours before defense ministers of NATO states were set to gather in Brussels for a summit, where Ukraine's security was among the topics to be discussed.
Ukraine's Foreign Minister Andrii Sybiha said, "One of the most popular questions asked by Muscovites this morning is 'What is going on?'" He added, "I can answer. Your country started a war of aggression against ours. For years, it has been killing our people. Now that you know what's going on, ask Putin when he is planning to end it."