Maybe they sneaked some of their explosives-laden drone vessels into the heavily-defended port. Maybe they fired a ballistic missile or a cruise missile. Maybe saboteurs sneaked into Sevastopol.

For the battered Russian Black Sea Fleet, how doesn’t really matter right now. What matters is fighting the fires raging across a drydock that exploded early Wednesday morning. A drydock that reportedly cradled two warships: a Ropucha-class amphibious vessel and a Kilo-class submarine.

If the Russians can’t put out the fires, and quickly, the Black Sea Fleet could lose two more of its roughly 30 large ships—ships it can’t replace until Russia’s wider war on Ukraine ends and Turkey reopens the Bosphorus Strait connecting the Black Sea to the Mediterranean Sea.

[Ukraine is sneaking up on Crimea. This has both strategic and morale value for the Ukranians, and it represents a clear danger to Russia’s entire Black Sea fleet. They need those shipyards and docks to continue its mission to blockade Ukraine and provide one of the last lines of communication to their Crimean occupation. — Ed]