The damaged flagship of Russia's Black Sea fleet has sunk, the country's Ministry of Defence has said.
Ukrainian officials say they hit the vessel with missiles, while Russia acknowledged a fire onboard the Moskva but no attack.
Western officials could not confirm what started the blaze.
The warship is named after the Russian capital, and her loss is a symbolic defeat for Moscow as its troops regroup for a renewed offensive in eastern Ukraine after retreating from much of the north, including the capital.
According to the Russian Defence Ministry, the ship sank in a storm while being towed to port. Russia had earlier stated the fire forced the entire crew to evacuate.
It later said the flames were contained and the vessel would be towed to port with its missile launchers intact.
The ship can carry 16 long-range cruise missiles, and its removal from combat reduces Russia’s Black Sea firepower.
It is also a blow to Russian pride in a war already widely seen as an historic blunder.
Now coming into its eighth week, Russia's invasion has stalled because of resistance from Ukrainian fighters boosted by weapons and other Western aid.