Senior Ukrainian officials visited Washington on Tuesday seeking U.S. support against Russia, as Kyiv showed its ability to fight on by setting off an explosive device under a bridge that has become a symbol of the Kremlin's claims on Ukrainian territory.

Ukraine unleashed more than a hundred drones smuggled deep into Russia in what it called its most damaging attack yet.

Ukraine says it hit the bridge with underwater explosives - the crossing was built by Russia after it annexed the Crimean Peninsula.