Ukraine said on Monday Russian drones fell and detonated on the territory of NATO member Romania during an overnight attack on Ukrainian port infrastructure on the Danube River, but Bucharest categorically denied the report.
Reuters could not independently verify either account of what could represent a dramatic turn in Russia's 18-month-old war in Ukraine. Moscow has regularly conducted long-range air strikes on targets in Ukraine, which borders Romania.
"According to Ukraine's state border guard service, last night, during a massive Russian attack near the port of Izmail, Russian 'Shakheds' fell and detonated on the territory of Romania," Ukrainian foreign ministry spokesperson Oleg Nikolenko wrote on Facebook.
"This is yet another confirmation that Russia's missile terror poses a huge threat not only to Ukraine's security, but also to the security of neighboring countries, including NATO member states," he said.
The Romanian Defense Ministry issued a statement in which it said it "categorically" denied the Ukrainian assertion.
NATO has a collective defense commitment under which the military alliance considers an attack on one ally to be an attack on all allies.
Nikolenko published a photo showing the flames of an explosion on the opposite bank of the Danube river, the dividing line between Ukraine's Odesa region and Romanian territory.
A Ukrainian industry source told Reuters that two Russian drones had fallen on the Romanian side.
The Ukrainian president's chief of staff said the incident showed the need to increase supplies of modern air defense and long-range weapons to deprive Russia of the ability to launch drones and missiles as Ukraine.
"Additional weapons and long-range missiles for Ukraine - to speed up the de-occupation of our territories. Russia must be defeated on the battlefield," the official, Andriy Yermak, wrote on the Telegram messaging app.
Ukraine's Danube ports, Reni and Izmail, accounted for around a quarter of grain exports before Russia pulled out of a UN-backed deal that provided safe passage for the export of Ukrainian grain via the Black Sea.
The Danube ports have since become the main route out of Ukraine, with grain also sent on barges to Romania's Black Sea port of Constanta for shipment onwards.
The overnight attack on Ukrainian port infrastructure took place hours before scheduled talks between Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan.
