Russia said it had neutralised two Ukrainian drones over Moscow in the early hours of Monday, with one crashing close to the defence ministry in the city centre.
Officials said the drones struck non-residential buildings in the capital and there were no casualties.
The attack came a day after Kyiv vowed to "retaliate" for a Russian missile attack on the Black Sea port of Odesa.
"A Kyiv regime attempt to carry out a terrorist act using two drones on objects on the territory of the city of Moscow was stopped," Russia's defence ministry said.
"Two Ukrainian drones were suppressed and crashed. There are no casualties."
The TASS news agency reported one drone crashed in Komsomolsky Prospekt, near the defence ministry, while another hit a business centre on Likhacheva Street by one of Moscow's main ring roads.
AFP reporters at the scene saw a building with a damaged roof on Komsomolsky Prospekt, where police had cordoned off the area.
Several police cars and fire engines and an ambulance could be seen and an AFP reporter was instructed by a police officer to stop filming or face detention.
"I wasn't asleep. It was 3:39am. The house really shook," Vladimir, a 70-year-old local resident, told AFP about the moment of impact.
"It is scandalous that a Ukrainian drone almost flew into the defence ministry," said Vladimir, who declined to give his last name, as he took pictures at the scene.
Moscow Mayor Sergei Sobyanin said the drone strikes occurred at around 4:00 am local time (0100 GMT).
He said emergency services were working at the scene and also reported no casualties.
The RIA Novosti news agency posted a video of the business centre, with some damage visible to the top of the tall building.
The road around it was closed.
Moscow and its environs lie around 500 kilometres (310 miles) from the Ukrainian border but have been hit by several drone attacks this year, with one even hitting the Kremlin in May.
Earlier this month, Russia said it had downed five Ukrainian drones that disrupted the functioning of Moscow's Vnukovo international airport.
- 'Will definitely feel this' -
Russian forces have pounded the Ukrainian port city of Odesa since Moscow quit a deal allowing Ukrainian grain to be exported through the Black Sea last week.
The latest strike on the city on Sunday killed two people and severely damaged a historic cathedral.
Clergymen rescued icons from rubble inside the badly damaged Transfiguration Cathedral, which was demolished under Stalin in 1936 and rebuilt in the 1990s after the collapse of the Soviet Union.
The Ukrainian government condemned the cathedral strike as a "war crime", saying it had been "destroyed twice: by Stalin and Putin".
President Volodymyr Zelensky vowed retaliation: "They will definitely feel this," he said.
"We cannot allow people around the world to get used to terrorist attacks," Zelensky added in his evening speech late on Sunday.
"The target of all these missiles is not just cities, villages or people. Their target is humanity and the foundations of our entire European culture."
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