The leaders of the five countries bordering the Caspian Sea have signed a landmark agreement on its legal status.
The agreement signed Sunday in Aktau, Kazakhstan, by the presidents of Russia, Iran, Azerbaijan, Turkmenistan and Kazakhstan comes after more than 20 years of negotiations on how to divide the resources of the world's largest inland body of water.
The pact establishes rules for declaring each country's territorial waters and fishing zones, but it fails to address how to deal with the seabed, which has potentially vast oil and gas reserves.
WATCH: Caspian Sea agreement
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Five Caspian Nations Agree on Status of Resource-rich Sea
Iranian President Hasan Rouhani, according to the news agency Interfax, said "this issue will be settled additionally in the course of agreements between the relevant parties.''
Until the fall of the Soviet Union, the sea had been considered equal territory of Moscow and Iran. But as new border states emerged the configuration of territory became an issue.
Tehran has insisted on either splitting the sea into five equal parts or jointly developing all of its resources. None of its neighbors have agreed to those proposals.
Speaking to reporters after the signing the deal Sunday, all five leaders praised it as historic event, but provided little detail about provisions on splitting the seabed.