That is why the Black Sea is crucial in the war

Here are all the ingredients for a geopolitical cocktail.

The only entrance and exit route is through the heavily trafficked Bosphorus, under the control of NATO country Turkey.

Along the western side are Bulgaria and Romania with several NATO bases.

In the port cities of northern Ukraine and on the eastern side Russia.

And in the middle the Crimean peninsula, annexed by Russia and home to the giant Black Sea Fleet.

- At the Black Sea, several different powers meet, and this has been the case for thousands of years, says Hugo von Essen, analyst at the Center for Eastern European Studies.

See Hugo von Essen's map of why control of the Black Sea is so important in the video above.