Romania, which borders Ukraine, said an F-18 fighter on a NATO air policing mission had shot down a drone that breached its airspace during the latest attacks.
It did not specify the origin of the drone, which entered from Moldova, but a NATO spokesperson said it appeared to be Russian.
Russia struck Ukraine's largest grain export port on the River Danube near the Romanian border last week after stepping up attacks on Ukraine in recent weeks. Ukraine has also intensified attacks on Russian targets including oil refineries, and both sides have struck commercial vessels in the Black Sea.
In the latest attacks since Russia's invasion of Ukraine in February 2022, Russian forces struck Ukraine's biggest steel plant overnight in the industrial city of Kryvyi Rih, President Volodymyr Zelenskiy's home town.
At least two people were killed and 14 injured, Ukrainian officials said.
A Russian missile strike on Kyiv early on Sunday caused fires in at least two districts of the capital. The city's military administration said three people were injured.
Three others, including a child, were injured in drone attacks across the region.
Russia's Defence Ministry said it had downed 822 Ukrainian drones throughout the country in the latest attacks.
Moscow region Governor Andrei Vorobyov said an 83-year-old man had been killed in what he described as one of the largest Ukrainian drone attacks on the Moscow region since the start of the conflict.
He said several people were also injured in the Podolsk area, and that a warehouse belonging to Russia's largest online retailer, Wildberries, had been struck.
Video filmed by Reuters after the strike on Wildberries' Koledino warehouse showed a large plume of smoke over the site, about 45km south of Moscow.
Ukraine has been targeting Wildberries, which it accuses of handling military goods, in recent weeks as part of a wider bid to damage Russian economic infrastructure it sees as underpinning Moscow's military campaign.
One person was also killed in a drone strike on a bus near the southern Russian city of Belgorod, the regional governor said. The Belgorod region borders eastern Ukraine.
Ukraine's military said it had also hit a missile fuel production facility in Russia's Rostov region overnight. Russia did not immediately comment on the report.
In the fourth incident this year in which a drone has strayed into its territory, the Romanian defence ministry said an F-18 jet that is part of a Spanish NATO contingent had shot down a drone over Romania.
The ministry said fragments from the destroyed drone appeared to have fallen in an uninhabited area between two villages.
Russia did not immediately comment on the incident.
