The Russian defence ministry said that its air defence had downed all nine missiles launched from Ukraine over its western Belgorod region.
Belgorod borders Ukraine's Kharkiv region and has repeatedly come under fire since the beginning of Russia-Ukraine war in February 2022.
Russia's defence ministry said it thwarted Ukraine's "terror" attack on its objects by destroying nine missiles of the multiple-launch rocket system called "Uragan" (Hurricane) in the air.
NATO member Romania reported a possible violation of its airspace during overnight drone attacks by Russia on infrastructure in neighbouring Ukraine.
Since exiting a deal allowing safe grain shipments via the Black Sea, Moscow has ramped up strikes on Ukraine's southern Odesa and Mykolaiv regions, home to vital grain-exporting infrastructure.
"Following the detection of groups of drones heading towards Ukrainian territory near the Romanian border" residents in the Tulcea and Galati municipalities were alerted, the defence ministry said in a statement.
"The radar surveillance system indicated possible unauthorised entry into national airspace, with a signal detected on a route towards the municipality of Galati," it added.
The defence ministry said that no objects so far appear to have fallen on Romanian territory but the search will continue on Saturday.