The leaders of the five states bordering the resource-rich Caspian Sea signed a landmark deal on its legal status on Sunday in the Kazakh city of Aktau, easing regional tensions and potentially facilitating lucrative oil and gas projects. Iranian President Hasan Rouhani, according to the news agency Interfax, says “this issue will be settled additionally in the course of agreements between the relevant parties.”

The legal status of the Caspian Sea, the world’s largest inland body of water, had been unresolved since the 1991 collapse of the Soviet Union. The difficulty of determining the status of the Caspian sea are related, in particular, with the recognition of its lake or sea, the delimitation of which is governed by different provisions of international law. By the end of the summit, the sides plan to sign the main outcome document, Convention on the Legal Status of the Caspian Sea, which was finalized at the Caspian Foreign Ministers Meeting in Moscow late 2017. “The Caspian Sea only belongs to the Caspian states,” he said.Putin also praised this clause, saying it would help “ensure the peaceful status of the Caspian Sea.”

The deal provides a means of delimiting national boundaries in the sea whose underground energy resources are estimated at 50 billion barrels of oil and just under 300 trillion cubic feet (8.4 trillion cubic metres) of natural gas.
After more than 20 years of negotiations, the five countries bordering the Caspian Sea sign an agreement in Aktau, Kazakhstan, on its shared use and the distribution of its resources. The convention legally defines the body of water as a sea rather than a lake, but with special provisions.