Bucharest and Kyiv's senior officials have condemned the attack, claiming Russia was behind it.
ADVERTISEMENTA suspected Russian missile struck a Turkish-operated cargo ship delivering Ukranian grain to Egypt, roughly 48 kilometres off the Romanian coastline on Thursday, authorities in Kyiv and Bucharest said.
Ukrainian officials said in a statement that the missile had been launched by a Russian strategic bomber.
In a Facebook post on Thursday, Ukrainian President Volodymyr Zelenskyy said there were no casualties in the incident, while photographs supplied by his office show significant damage to parts of the vessel.
The strike occurred outside national waters but within Romania's exclusive maritime economic zone.
Romania's Defence Minister Angel Tîlvăr responded to the event by stating the Black Sea is "no longer a space of cooperation — but a war theatre".
"Romania strongly condemns the unprovoked and illegal Russian aggression against the Ukrainian people, especially the attacks on the Ukrainian civilian population and infrastructure," he said.
Romania's Ministry of Foreign Affairs also condemned the attack, calling it "an unprecedented escalation" of Russia's war in Ukraine.
"Deliberately targeting a cargo ship constitutes a serious violation of international humanitarian law governing the conduct of warfare at sea," the department said in a press release.
US Ambassador to Ukraine Bridget A. Brink also condemned the attack and called it "an escalation and a blatant violation of international law that threatens global food security".
Moscow claims it has no information about an attack. According to the state-run Tass news agency, Kremlin spokesman Dmitry Peskov said that “the Kremlin is not familiar with accusations from Kyiv that Russia allegedly attacked a grain ship in the Black Sea.”