Drones then hit two merchant ships, one of which sank. Everyone on board the sunken ship - about 10 people, according to a Bulgarian maritime traffic monitor - is now presumed dead.
“Such an attack within Bulgaria’s exclusive economic zone is completely unacceptable,” Bulgarian Prime Minister Rumen Radev told reporters on Tuesday.
Bulgarian authorities have not yet determined where the drones came from. Both Russia and Ukraine regularly attack ships in the Black Sea, but Tuesday’s attack was the first against shipping in Bulgaria’s exclusive economic zone.
All 18 crew members aboard the second ship survived.
