Romania's defence ministry reported on Thursday the discovery of a drone crater near the country's border with Ukraine following Russian attacks on Ukrainian port infrastructure on the previous evening.
Russia has been targeting Ukrainian ports and warehouses along the Danube between Ukraine and NATO member Romania since pulling out of a deal in July that had allowed Kyiv to export grain from its Black Sea ports. The strikes seem designed to choke off the main alternative route for Ukraine's farm exports.
In that time, Romania has reported isolated incidents of drone parts landing in the country, although it has said Romanian territory was not the intended target.
The defence ministry said on Thursday there was a "possible explosion on impact" at the crater, measures had been taken to secure the area, and forces would continue to monitor Romanian airspace.
"The Ministry of National Defence strongly condemns the attacks carried out by the Russian Federation against some objectives and elements of civil infrastructure in the Ukrainian ports on the Danube," it said.
"These attacks are unjustified and in serious contradiction with the rules of international humanitarian law."
Following a previously scheduled defence council meeting on Thursday where drone attacks were discussed, the Romanian president's office said the defence ministry planned measures to increase aerial surveillance, detection and intervention. It gave no specific details.
"The intensification of Russian drone attacks on Ukraine's sea and river ports in the Black Sea area has brought the war even closer to Romania's borders," the president's office said.
"Incidents with fragments of drones falling on the territory of our country and implicitly of NATO have increased the risk of escalation."
