NATO vows to adjust defences after drones hit 2 ships off Bulgaria

NATO Secretary General Mark Rutte said Tuesday the alliance will adjust its defenses “as needed” after two ships were struck in the Black Sea off Bulgaria.

“We have already strengthened our posture along the eastern flank and will continue to monitor the security environment,” Rutte wrote on X.

Bulgarian Prime Minister Rumen Radev said earlier Tuesday that drones hit two ships, sinking one and prompting emergency rescue operations. The strikes occurred 27 to 29 kilometers (about 17 to 18 miles) from the Bulgarian coast.

Rescuers evacuated all 15 crew members from the Maltese-flagged Chelsea 3, Radev said in a video posted to social media. Five received treatment for minor injuries. The crew included seven Ukrainians and eight Azerbaijanis, who reported that three aerial drones hit the ship’s deck and hull.

Radev said one crew member from the sunken vessel was rescued but gave no details on the others aboard. At least 11 sailors remain missing at sea.

At an emergency meeting of Bulgaria’s Security Council, Radev called the attacks “absolutely unacceptable” and said Bulgaria is seeking NATO and European Union assistance.

Authorities do not have clear evidence of who was responsible, Radev said. But he said “logic” points to Russia as the beneficiary. He said he would summon the Russian ambassador to Bulgaria, Eleonora Mitrofanova, later Tuesday.

Russia did not immediately comment.

Ukrainian Foreign Minister Andrii Sybiha blamed Russia on X, saying Moscow was showing deliberate disregard for civilian lives and maritime security. He urged Ukraine’s partners to increase pressure on Russia, strengthen sanctions and protect freedom of navigation. “The Black Sea is a lifeline for global food security,” he wrote.

European Commission President Ursula von der Leyen “strongly condemned” the attacks and said the Black Sea “has become another front of escalation” in Russia’s war in Ukraine. She said the EU stands with Bulgaria and called for those responsible to be held accountable.

The strikes came exactly a week after sea and aerial drones attacked two other commercial vessels in Bulgaria’s exclusive economic zone. A Togo-flagged ship sank, and a Bulgarian ferry evacuated the 18-member crew of a Pulau-flagged vessel. Ukrainian President Volodymyr Zelenskyy said Ukraine’s military conducted no operations near the site of those strikes and pointed to Russia.

Separately, a Turkish-owned cargo ship carrying corn caught fire after a drone attack and sank off the coast of Romania, Romanian authorities said. Two people died and 11 crew members were rescued.

Black Sea security

The incidents have renewed scrutiny of Europe’s ability to protect shipping and critical infrastructure in the region. The EU launched a Black Sea Security Strategy in May 2025, when EU foreign policy chief Kaja Kallas called the region “the prime target for hybrid actions.”

The strategy aims to secure the maritime corridor and protect assets such as offshore installations and subsea cables. It also promised a Black Sea Maritime Security Hub to coordinate support and boost coast-guard cooperation. The hub would analyze seabed sensor data and alert allies to potential threats.