Eleven sailors were missing on Tuesday after a drone strike sank a cargo ship off the Bulgarian coast — quite possibly the second fatal sinking of a merchant vessel in those waters within a week. Bulgaria has summoned Russia's ambassador.

Two cargo ships were hit by drones overnight, Bulgarian officials said. One went down off the village of Krapets, near the Romanian border. Five crew members were rescued; 11 remained missing as a search and rescue operation continued. President Iliana Iotova identified the sunken vessel as the Guinea-Bissau-flagged bulk carrier HS Dignity.

The second ship, the Maltese-flagged Chelsea-3, was struck by three drones overnight but stayed afloat. All 15 crew — seven Ukrainians and eight Azerbaijanis — were rescued, none seriously injured.

Which ships were hit?

Ship tracking data on LSEG and MarineTraffic fills in the commercial picture. The Chelsea-3 called at the Romanian port of Tulcea on October 3 before sailing toward the Bulgarian coast. It was showing 72% of full load, cargo onboard.

The HS Dignity, also part-loaded, was bound for the Romanian Danube port of Braila and had previously called at Mostaganem, Algeria. In other words, both vessels were working the coastal and river-sea trades that Ukrainian grain exports have been pushed onto since Russia began bombing Ukraine's Black Sea ports.

A week earlier, nine Syrian sailors and one Egyptian were lost when drones sank a ship inside Bulgaria's Black Sea exclusive economic zone. A second ship was hit that same night; its crew was rescued.

What does Bulgaria say?

Prime Minister Rumen Radev stopped short of naming Russia as the attacker, but left little doubt about where he thought responsibility lay.

"This is absolutely unacceptable — another attack in the immediate vicinity of Bulgarian territorial waters," Radev said in a televised address. The outcome of the attacks, he said, "benefits the Russian Federation."

There was no immediate comment from Moscow. After meeting Radev in Sofia, Russian Ambassador Eleonora Mitrofanova said she had no information from the Russian Defence Ministry about attacks on commercial vessels in the Black Sea — and did not rule out a provocation by a third party, according to the Bulgarian government.

Radev spoke by phone with European Commission President Ursula von der Leyen and NATO Secretary General Mark Rutte, urging support to strengthen Bulgaria's maritime and airspace surveillance. Rutte said NATO would continue adjusting its military presence on the eastern flank "as needed." Defence Minister Dimitar Stoyanov discussed Black Sea security with his Romanian and Turkish counterparts.

Who condemned the strikes?

Ukraine and the EU both reacted sharply.

"The Black Sea has become another front of escalation of the Russian war in Ukraine," von der Leyen said on X. "Those responsible should be held accountable."

Ukrainian Foreign Minister Andrii Sybiha said the strike "once again demonstrates Moscow's deliberate disregard for civilian lives." He added: "The Black Sea is a lifeline for global food security. Russia is attacking it to weaponise hunger and hold the world hostage."

Why does this matter for shipping?

More than four and a half years into the war, Black Sea shipping has become a battle of economic endurance — and neutral-tonnage crews are paying the price. Both Ukraine and Russia rank among the world's largest grain exporters.

Russia's bombing campaign against Ukraine's Black Sea ports has forced Kyiv to lean ever harder on Danube river ports and on coastal routes hugging the shores of NATO members Bulgaria and Romania. Those are precisely the waters where HS Dignity and Chelsea-3 were sailing.

Ukraine, for its part, has increasingly targeted Russian grain-exporting ships in other parts of the Black Sea and in the Azov Sea at the mouth of the Don.

The commercial logic is brutal. Coastal transits that offered relative safety from the war's northern reaches now carry drone risk of their own, and insurers pricing Bulgaria-to-Romania coastwise traffic will take note. Two sinkings in a week, with 21 crew dead or missing across both incidents, marks an escalation from harassment to lethal outcomes in NATO-adjacent waters.

Expect pressure on NATO to widen surveillance coverage of the western Black Sea — and war-risk premiums on the Danube corridor trades to harden as underwriters digest the HS Dignity loss.