Meeting in the Kazakh port city of Aqtau, the leaders of Azerbaijan, Iran, Kazakhstan, Russia, and Turkmenistan have signed a new convention on the legal status of the resource-rich Caspian Sea -- a matter disputed between the five neighbors for more than 20 years.
The leaders provided no details of the agreement in their speeches before the signing of the document.
Analysis: A Landmark Caspian Agreement -- And What It Resolves
Russian President Vladimir Putin said the settlement of the Caspian Sea's legal status "creates conditions for bringing cooperation between the countries to a qualitatively new level of partnership, for the development of close cooperation on different trajectories."
His Iranian counterpart, Hassan Rohani, said that the delimitation of oil- and gas-rich Caspian seabed will require additional agreements between littoral states.
Rohani also hailed a clause in the convention that prevents non-Caspian countries from deploying military forces on the Caspian Sea, saying, "The Caspian Sea only belongs to the Caspian states."
And Kazakh President Nursultan Nazarbaev said the agreement allows for the construction of underwater oil and gas pipelines, as well as setting national quotas for fishing.
The parties agreed to set up a "special mechanism of regular five-party consultations under the auspices of the Foreign Ministries" to implement the provisions of the convention, Nazarbaev also said.
The summit was also attended by Azerbaijani President Ilham Aliyev and Gurbanguly Berdymukhammedov of Turkmenistan.
The five countries also signed agreements on trade and economic relations, transportation, and the fight against terrorism.
Debates on whether the Caspian is a sea or a lake have been ongoing since the Soviet Union fell apart in 1991, leaving five countries with shorelines on the inland sea instead of two -- the Soviet Union and Iran.
If deemed a sea, the five countries would draw lines extending from their shores to the midway point with littoral neighbors, while classifying it as a lake would mean the resources would be divided equally among those five countries.
The countries have been working on an agreement to resolve the issue since 1996, the Kremlin said.
At stake are resources including trillions of dollars' worth of hydrocarbons in the seabed, which holds about 50 billion barrels of oil and nearly 9 trillion cubic meters of natural gas in proven or probable reserves.
A draft of the agreement, posted briefly on Russian Prime Minister Dmitry Medvedev’s website in June and obtained by RFE/RL, suggested that the countries would agree in Aqtau that the Caspian is a sea.