Romania says a Russian drone has breached its airspace - the second NATO country to report such an incursion.
Romanian fighter jets were in the air monitoring a Russian attack in Ukraine on Saturday and tracked the drone near Ukraine's southern border, according to the country's defense ministry.
Ukrainian President Volodymyr Zelensky described the incursion as not a mistake but an obvious expansion of the war by Russia. Moscow has yet to comment on the Romanian claims.
On Wednesday, Poland reported that it had shot down at least three Russian drones that had entered its airspace.
In its statement, Romania's defense ministry indicated that the Russian drone was detected by two F-16 jets monitoring the country's border with Ukraine, at the time of ongoing Russian air attacks on Ukrainian infrastructure on the Danube.
The drone was located 20 km (12.4 miles) south-west of Chilia Veche village but did not pass over populated regions or present an immediate danger, the ministry noted.
The European Union's foreign policy chief, Kaja Kallas, condemned the incident as a violation of an EU member state's sovereignty.
Poland also took action following this incident, with Prime Minister Donald Tusk stating that preventative aviation operations were initiated in Polish airspace, and ground-based air defense systems were put on high alert.
This increase in military readiness comes on the heels of various drone incursions reported by both Poland and even discussions surrounding NATO's eastern flank integrity following heightened Russian military activity.
President Zelensky asserted that the Russian military is aware of their drone operations' trajectories and urged Western nations to impose stricter sanctions on Moscow.
Overall, as tensions escalate with Russia's ongoing aggression in Ukraine, NATO allies are tightening their defense postures in the region.
