Updated Tuesday morning: Drones struck two cargo ships early Tuesday inside Bulgaria's part of the Black Sea, and one of them sank, Prime Minister Rumen Radev said. He said air and sea drones hit the ships around 3 a.m. local time, more than 100 kilometers off the coast near the town of Byala. The Associated Press called it the first attack on shipping in the NATO member's economic zone.

The Alfa Watan, a Turkish-owned cargo ship flying the flag of Togo, was badly damaged and went down at the scene. There was no word on its crew, and the search went on through the morning. The second ship, the Palau-flagged Able, caught fire while carrying wheat. A Bulgarian ferry took off all 18 crew members, and two who were badly hurt were flown to a hospital in the port city of Varna. The BBC said 11 of the Able's sailors were Turkish and seven were Indian.

No one has said who sent the drones. Radev called the strike "a blatant violation of international law and maritime law." He said it is "seriously disrupting shipping in the Black Sea" and pushing insurance costs even higher, and officials are watching for oil spills. NATO declined to comment and sent questions to Bulgaria, while European Commission President Ursula von der Leyen said attacks on civilian ships are unacceptable.

The strike came one day after the Royad Mammadov, a Turkish-owned grain ship, sank about 30 nautical miles off Romania, where officials confirmed two dead and 11 rescued. Azerbaijan said the ship's captain, Rustam Hasanov, was killed and a young Azerbaijani sailor is still missing. Ukrainian President Volodymyr Zelensky blamed two Russian drones. Romania has confirmed only a fire and has not named a cause.

The Black Sea has grown far more dangerous since Russia invaded Ukraine in 2022. Turkey's Chamber of Maritime Commerce says 226 civilian and commercial ships have been attacked there since the war began. Bulgaria's economic zone covers just over 29,000 square kilometers, about 6% of the sea, the BBC reported. Both Bulgaria and Romania are NATO members, and both sit on the sea's western shore.

What we know: Two ships were hit off Bulgaria, one sank, and its crew has not been found.
What we don't: Who launched the drones in either attack.