In World War II, the Soviet Union used submarines (as well as other ships) to supply the besieged Crimean port of Sevastopol.

In the 1570s close to 20,000 slaves a year were being sold in the Crimean port of Kaffa.

But Kiev insists that Russia will only be allowed use of one Crimean port and wants to retain Sevastopol exclusively for the Ukrainian fleet.

Also, there were a number of Crimean ports under Mongol control, so it is unlikely that Caffa was the only source of plague-infested ships heading to Europe.

Disagreements and tensions arose, particularly over ownership of the Black Sea Fleet harboured in the Crimean port of Sevastopol.

Allied forces took over the Crimean ports, in support of the loyalist White Army, which temporarily allowed the surviving members of the Romanov family time to escape abroad.

The treaty also gave Russia the Crimean ports of Kerch and Enikale and the Kabarda region in the Caucasus.

Ukraine had eleven closed cities: among them the Crimean port of Sevastopol and the industrial city of Dnipropetrovsk, though both were restricted to foreigners, not locals.

Ottoman forces were being transferred from the Danube front to the Crimean port of Eupatoria and the town was being fortified.

It includes a declaration claiming the Crimean port of Sevastopol to be Russian, not Ukrainian - and another condemning the United Nations Security Council for denouncing the measure.