President Zelensky has described seaborne drones as Ukraine’s “eyes and protection on the frontline”, with claims of a series of successful strikes against Russian ships in the Black Sea and on a key bridge to Crimea.

These remote-controlled devices are playing an increasingly prominent role, with both sides ramping up their use for attacks and reconnaissance.

The BBC’s Security Correspondent Frank Gardner and BBC Verify examine their influence on the conflict.

Production: Soraya Auer

Motion Graphics: Jacqueline Galvin

Verification: Tom Spencer, Paul Brown, Emma Pengelly, Richard Irvine-Brown