Bulgaria summons Russia after ships struck off Black Sea coast
Bulgarian Prime Minister Rumen Radev has summoned the Russian ambassador after two merchant ships were struck by drones off the region's Black Sea coast.
One ship sank, six crew members were rescued - but 10 more are missing, according to recent reports.
UK correspondent Gavin Grey says this attack comes a week after two other ships were attacked by drones in Bulgaria's exclusive economic zone.
LISTEN ABOVE
Take your Radio, Podcasts and Music with you