The overflight with an attack drone was strongly condemned in Bucharest, which called the event an "illegitimate attack" by Moscow. The Air Force was ordered to patrol the border.
The incident occurred in connection with an attack on "civilian targets and infrastructure at the port" on the other side of the Danube River in neighboring Ukraine, according to Romania's Defense Ministry. Romania said that Russian airspace violations are a recurring problem.
Residents in the regions of Tulcea and Constanta near the border with Ukraine were informed by phone about the overflight.
Remains of Russian drones have previously been found in NATO territory, since Russian military has carried out extensive attacks on Ukrainian port cities along the Black Sea coast.
According to media reports, a Russian drone has crashed in the Rezekne region of Latvia, also a NATO country, reports Aftonbladet citing the Latvian LSM. The military alliance NATO has received information about both incidents.