Scuttling.

This is coolbert:

Thanks to Bubbleheads we have the info on the most recent episode of naval scuttling to deny a port access to hostile warships.

"The Weird War History of 'Strategic Scuttling' "

"Russians (or Russian sympathizers) sank a ship to block Ukraine's access to an important harbor. This tactic isn't as unusual as you might think."

"As the Ukrainian-Russian rift over Crimea intensifies, a new tactic has emerged: intentionally sinking a ship to prevent Ukrainian government ships from leaving a southern port."

IN THIS PARTICULAR INSTANCE THE RUSSIANS SCUTTLING A SHIP TO PREVENT THOSE NAVAL VESSELS IN PORT FROM SAILING.

That Russian even we might consider a master of such military technique. Consider from the Crimean War:

"During the Crimean War, in anticipation of the Siege of Sevastopol, the Russians scuttled ships of the Black Sea Fleet to protect the harbor, to use their naval cannon as additional artillery, and to free up the ships' crews as marines . . .  After the war, it became a technological challenge to recover the ships."

Those sunken ship representing a considerable force, even perhaps the ENTIRE RUSSIAN BLACK SEA FLEET DELIBERATELY SENT TO THE BOTTOM. Preventing enemy egress into Sevastopol.

coolbert.