Iran and four ex-Soviet nations, including Russia, agreed in principle on Aug. 12 how to divide up the potentially huge oil and gas resources of the Caspian Sea, paving way for more energy exploration and pipeline projects.

However, the delimitation of the seabed, which has caused most disputes, will require additional agreements between littoral nations, Iranian President Hassan Rouhani said.

For almost three decades, the five littoral states—Russia, Iran, Kazakhstan, Turkmenistan and Azerbaijan—have argued over how to divide the world’s biggest enclosed body of water.

And while some countries have pressed ahead with large offshore projects such as the Kashagan oil field off Kazakhstan’s coast, disagreement over the sea’s legal status has prevented some other ideas from being implemented.

One of those is a pipeline across the Caspian which could ship natural gas from Turkmenistan to Azerbaijan and then further to Europe, allowing it to compete with Russia in the Western markets.

Some littoral states have also disputed the ownership of several oil and gas fields, which delayed their development.

“We have established 15-mile-wide territorial waters whose borders become state borders,” Kazakhstan President Nursultan Nazarbayev told a briefing after signing the Caspian convention.

“Adjacent to the territorial waters are 10 miles of fishing water where each state has exclusive fishing rights,” he said.

Nazarbayev also said the convention explicitly barred any armed presence on the Caspian Sea other than that of the littoral states.