Ukrainian, Russian warships on the move in key Black Sea channel

(CNN) – Russian troops have taken positions in Ukraine's Crimea peninsula, as world leaders scramble to find a solution to this conflict.

Now, moves at sea are also raising the stakes, in a key channel into the Black Sea, a Turkish waterway identified as a world oil transit choke point by the U.S. government.

The Bosphorus Strait was the scene of a tense situation involving a key Ukrainian warship that CNN's Ivan Watson was tailing off the coast of Turkey.