Rumen Radev, Bulgaria’s prime minister, has summoned Russia’s ambassador following drone attacks on two merchant ships near its Black Sea coast. The Guinea-Bissau-flagged HS Dignity sank approximately 31 kilometres offshore, with six crew members rescued and ten missing. All fifteen crew members aboard the Ukrainian-owned Chelsea-3 were rescued, although five sustained minor injuries. The incidents followed an earlier attack on two other vessels in Bulgarian waters; one sank, with ten crew members presumed dead. Radev condemned the attacks and sought discussions with NATO, while acknowledging that responsibility had not been conclusively established. Russia’s ambassador denied having information about the incidents and suggested possible third-party involvement. NATO pledged continued vigilance in the Black Sea. The attacks heighten concerns about the conflict in Ukraine spreading towards NATO territory.