Two merchant ships came under drone attack off Bulgaria early Tuesday, with one reportedly sunk roughly 17 nautical miles east of Krapets, as the maritime war spread across the western Black Sea.

The Maltese-flagged, Ukrainian-owned general cargoship Chelsea 3 was struck by three aerial drones about 18 nautical miles east of Byala. All 15 crewmembers — seven Ukrainians and eight Azerbaijanis — were rescued by Bulgarian border police and taken to Varna. Eight went to hospital, three of them with burns.

A second vessel, identified by local maritime media as the St Kitts and Nevis-flagged general cargoship Azov Concord, was reportedly sunk east of Krapets. Five seafarers were rescued by passing merchant ships. The status of the remaining crew remains unclear.

Bulgarian prime minister Rumen Radev announced the sinking, though interior ministry officials later said the vessel's fate had not been conclusively established. The discrepancy matters for insurers and owners. A confirmed total loss triggers a very different claims process than a damaged-but-salvageable hull.

Radev condemned the attacks as "absolutely unacceptable", announcing plans to summon Russia's ambassador and seek assistance from NATO and the European Union. He acknowledged there was insufficient evidence to conclusively identify the attackers, while suggesting the strikes appeared to benefit Russia.

How did we get here?

The timeline is tight and getting tighter. Tuesday's incidents come exactly a week after two other merchant ships were attacked inside Bulgaria's exclusive economic zone. Those followed the sinking of the Royad Mammadov off Romania, which killed two seafarers.

Behind the escalation sits a broader Russian campaign against Ukrainian port infrastructure and commercial shipping. Earlier this month, Moscow claimed strikes against four cargo vessels in the northwestern Black Sea. A separate attack on a Liberian-flagged ship at an Odesa region port killed another seafarer.

So in under a month: Bulgaria hit twice, Romania once, Ukraine's ports repeatedly. The western Black Sea is no longer a fringe risk zone.

What does this change for shipping?

The commercial fallout is already visible in the numbers. Black Sea wheat loadings collapsed to 1.6m tonnes in September, down nearly 78% year-on-year, as attacks increasingly disrupt one of the world's most important grain export regions.

For shipowners, the mechanism is straightforward. War-risk premiums for Black Sea calls were already elevated; repeated strikes on neutral-flagged tonnage in Bulgarian and Romanian waters will push underwriters to reprice or restrict cover further. Malta, St Kitts and Nevis, Liberia — these are not Ukrainian flags, and that is the point. The threat now extends beyond vessels linked to either belligerent.

For charterers and grain traders, the 78% collapse in September loadings signals that export capacity, not just appetite, is being destroyed. Elevators fill, vessels stay away, and the world's grain buyers look to other origins at higher cost.

Crewing agencies face their own pressure. Casualties are no longer theoretical — two dead on the Royad Mammadov, one more at Odesa, burns among the Chelsea 3 crew. Retention and wages for Black Sea routes will reflect that.

What happens next?

Radev's moves — summoning the Russian ambassador, appealing to NATO and the EU — point toward a diplomatic escalation, but no immediate security guarantee for commercial traffic. Bulgaria lacks the naval footprint to patrol its exclusive economic zone against drone threats on its own.

Unless convoys, escorts or a ceasefire materialise, the trajectory is clear: attacks are spreading westward from Odesa toward Bulgarian and Romanian waters, and September's 1.6m-tonne wheat figure may not mark the floor.