Until the collapse of the Soviet Union in 1991, use of the Caspian Sea was governed with treaties signed by the Soviets and Iranians. Now four countries that emerged from the rubble of the Soviet collapse have claims on the Caspian. They include Russia, Kazakhstan, Azerbaijan and Turkmenistan.

Russia, Azerbaijan and Kazakhstan favour dividing the sea along median lines, which will give Iran the smallest sector. The Iranians for their part want to split it up equally.