Eleven sailors went missing at sea Tuesday on a ship sunk by a drone attack off the coast of Bulgaria, possibly the second deadly sinking of a cargo ship in the area in a week, prompting Bulgaria to summon Russia’s ambassador. Two cargo ships were hit by drones overnight and one sank, Bulgarian officials said. Bulgaria stopped short of explicitly accusing Russia of carrying out the attacks, but Prime Minister Rumen Radev said their outcome “benefits the Russian Federation.” There was no immediate comment from Moscow on the incidents. “This is absolutely unacceptable: another attack in the vicinity of Bulgarian territorial waters,” Radev said in a televised speech. The attacks were also condemned by Ukraine and the EU. “The Black Sea has become another front of escalation of the Russian war in Ukraine”, Ursula von, president of the European Commission der Leyen in X. “Those responsible must be held accountable.” Ukrainian Foreign Minister Andrii Sybiha said on X on Tuesday that the attack “demonstrates once again Moscow’s deliberate disregard for civilian lives.” “The Black Sea is a lifeline for global food security. Russia is attacking it to weaponize hunger and hold the world hostage,” he said. reinforce maritime and airspace surveillance of their country, the Bulgarian government said in a statement. NATO will continue to adjust its military presence on its eastern flank “as necessary,” Rutte said. Bulgarian officials said five crew members had been rescued but 11 were still listed as missing from the ship that sank off the coast of the village of Krapets. President Iliana Iotova identified the ship as the Guinea-Bissau-flagged freighter HS Dignity and said a search and rescue operation was underway. Another ship, the Chelsea 3 sailing under the Maltese flag, was also hit by three drones overnight, Bulgarian officials said. The entire crew of that ship (seven Ukrainians and eight Azerbaijanis) were rescued and none were seriously injured. A week ago, nine Syrian sailors and one Egyptian were lost at sea after a ship sank after being hit by drones in Bulgaria’s exclusive economic zone on the Black Sea. Another ship was also hit that night, but the crew was rescued. After meeting Radev in Sofia, Russian Ambassador Eleonora Mitrofanova said she had no information from the Russian Defense Ministry about the attacks on commercial ships in the Black Sea, but did not rule out that they could be a provocation by a third party, the Bulgarian government said. More than four and a half years into the war Moscow launched with its full-scale invasion in 2022, Black Sea shipping has increasingly been drawn into a protracted battle of economic resistance. Russia is among the world’s largest grain exporters. Russia has been bombing Ukrainian Black Sea ports, forcing Ukraine to become increasingly dependent on Danube river ports and sea routes near the coasts of NATO members Bulgaria and Romania. Ukraine, for its part, has increasingly attacked Russian grain-exporting ships in other parts of the Black Sea and the Sea of Azov at the mouth of the Don River.