The Ukrainian navy has said it hit the Konstantin Olshansky landing ship with a missile.
Russia captured the ship from Ukraine in 2014.
"Currently, this ship is not combat-capable," said navy spokesperson Dmytro Pletenchuk said.
The Konstantin Olshansky was taken by Russia during the annexation of Crimea.
It appeared to have been repainted to Russian navy colours and given a new pennant number.
