A Brief History of the Legal Regime of the Caspian Sea

By Babak Cheraghi Merdasi

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Introduction

Drawing on the primary texts of historical treaties and archival documents, this writing examines the legal continuity between the Treaty of Gulistan of 1813 and the Treaty of Turkmenchay of 1828, as well as the evolution of the legal regime governing the Caspian Sea. It also examines the emergence of Russia’s exclusive right to maintain a military presence in the Caspian—a legal arrangement that, following the collapse of the Soviet Union and the emergence of three new littoral states, namely Kazakhstan, the Republic of Azerbaijan, and Turkmenistan, contributed to a complex five-party legal and political dispute over the status and governance of the Caspian Sea.

The Geographic and Physical Characteristics of the Caspian Sea

The Caspian Sea is the world’s largest enclosed body of water, with no direct natural connection to the open oceans, and lies between Europe and Asia. It is bordered by Iran to the south, Russia to the north, Russia and the Republic of Azerbaijan to the west, and Kazakhstan and Turkmenistan to the east.

The Caspian Sea covers an area estimated at approximately 371,000 to 436,000 square kilometres. Its distinctive geographical, environmental, economic, and geopolitical characteristics make it of exceptional importance to all five littoral states.

The Development of the Legal Regime of the Caspian Sea in the Modern Era

During the wars between Iran and Russia under the Qajar dynasty in Iran and the Russian imperial government, Iran’s military defeats resulted in the separation of large parts of its northern territories, including Ganja, Karabakh, Shirvan, Derbent, Baku, and parts of Talish, and their incorporation into the Russian Empire.

Alongside these territorial losses, the Treaty of Gulistan in 1813 and subsequently the Treaty of Turkmenchay in 1828 imposed significant restrictions on Iran’s military presence in the Caspian Sea. Article 5 of the Treaty of Gulistan and Article 8 of the Treaty of Turkmenchay confirmed Russia’s exclusive right to maintain warships in the Caspian, while commercial navigation by both Iran and Russia was recognized.

These two treaties therefore cannot be understood solely as the outcome of Iran’s military defeats. Iran’s diplomatic setbacks and its failure to secure effective support from the European powers, including Britain and France, also contributed to the circumstances that led to the conclusion of these treaties.

The Legal Regime of the Caspian between Iran and Russia during the Pahlavi Era

Following the fall of the Russian imperial government and the establishment of the Soviet Union, the previous legal regime underwent significant changes. The 1921 Treaty of Friendship between Iran and Soviet Russia, while abrogating many of the previous arrangements and agreements, recognized the right of both countries to free and equal navigation under their respective national flags in the Caspian Sea. Article 11 of the treaty explicitly affirmed the equality of the two parties’ rights of navigation in the Caspian.

This principle was reinforced in subsequent agreements between Iran and the Soviet Union, including agreements concerning commerce and navigation. The agreements of 1931, 1935, and 1940 further emphasized equal treatment with regard to navigation and certain fishing rights.

In particular, the 1940 Treaty of Commerce and Navigation, concluded during the reign of Reza Shah, further consolidated the framework governing maritime relations between Iran and the Soviet Union. Under this regime, the Caspian was, in practice, a sea shared by Iran and the Soviet Union, with the navigation rights of both countries organized on the basis of equality.

The Legal Regime of the Caspian Sea after the Collapse of the Soviet Union

Following the dissolution of the Soviet Union in 1991, the legal status of the Caspian became considerably more complex. Three newly independent states—Kazakhstan, the Republic of Azerbaijan, and Turkmenistan—became littoral states of the Caspian, increasing the number of states directly concerned with its legal regime from two to five.

After years of negotiations, the five Caspian littoral states—Iran, Russia, Kazakhstan, the Republic of Azerbaijan, and Turkmenistan—signed the Convention on the Legal Status of the Caspian Sea in 2018. The Convention divides the waters of the Caspian into internal waters, territorial waters, fishing zones, and a common maritime space. Under the Convention, each state may establish territorial waters extending up to a maximum of 15 nautical miles, followed by a 10-nautical-mile fishing zone.

An important point is that the 2018 Convention does not itself establish a specific percentage—such as 11, 13, or 20 percent—for any of the five states. The delimitation of the seabed and subsoil, particularly in areas between adjacent or opposite coastal states, is to be determined through agreements among the states concerned.

Nevertheless, one of the principal concerns in Iran regarding the negotiations over the division of the Caspian seabed has been the possibility that a particular delimitation model, if extended across the entire seabed, could significantly reduce Iran’s share of potential seabed and subsoil resources. Some calculations and proposals have estimated Iran’s potential share at approximately 13 percent. This issue has been strongly criticized by members of the Iranian public and opponents of such an approach.

Why Does the Caspian Matter to Iranians?

Opposition and concern among parts of the Iranian public regarding the new legal regime of the Caspian are not merely matters of legal interpretation. Historical memory, economic interests, national security, and questions of national identity all contribute to the sensitivity surrounding the issue. The principal concerns can be summarized as follows:

1. Historical Memory and Unequal Treaties

A significant part of Iranian society views any delimitation arrangement that could substantially reduce Iran’s access to the Caspian’s resources and potential as part of a historical continuum associated with the humiliating Treaties of Gulistan and Turkmenchay. These two treaties remain deeply embedded in Iranian historical memory as symbols of the loss of vast territories and the imposition of military restrictions on Iran in the Caspian Sea.

From this perspective, the concern is not simply about a particular percentage or numerical figure. Rather, it reflects the fear that, after a century and a half, Iran could once again find itself confronting a major power in an unequal arrangement and lose part of its historical rights and interests.

2. The Legal Argument

The 1921 Treaty and subsequent agreements between Iran and the Soviet Union, particularly the arrangements of 1931, 1935, and 1940, established an important legal basis for equality between the two countries in navigation and the use of the Caspian.

Following the collapse of the Soviet Union, the central question became how the rights and obligations arising from the previous legal regime should be interpreted and reconfigured under the new circumstances and in the presence of five littoral states. From the perspective of critics, the dissolution of the Soviet Union should not, by itself, constitute a basis for a substantial reduction in Iran’s rights in the Caspian.

3. Economic Considerations

The seabed and subsoil of the Caspian contain significant oil and gas resources, and the delimitation of the seabed and subsoil can directly affect the ability of the littoral states to explore and exploit these resources.

Consequently, any delimitation arrangement that reduces Iran’s access to parts of the seabed and its potential resources is also of fundamental economic importance to Iran.

4. Geopolitical and Security Considerations

The Caspian is an enclosed body of water of considerable strategic importance. Iran’s geographical position along its southern shore has not only economic significance but also important security and geopolitical dimensions.

From the perspective of critics, restricting Iran’s area of presence and activity in the Caspian could reduce its economic, maritime, and strategic room for manoeuvre and weaken Iran’s position in the regional balance of power surrounding this strategically important body of water.

Conclusion

For Iranians, the question of the Caspian Sea is not merely a matter of a few lines on a map or a dispute over a particular percentage. It lies at the intersection of history, international law, natural resources, national security, and the historical memory of a nation.

Gulistan and Turkmenchay remain alive in the historical memory of Iranians—not merely as historical documents, but as symbols of an era in which military defeat and diplomatic weakness resulted in territorial changes and restrictions on Iran’s power. For this reason, every new agreement concerning the Caspian is viewed with a sensitivity that goes far beyond a technical or purely legal dispute.

At the same time, a careful examination of the historical documents shows that navigation rights, fishing rights, and the delimitation of the seabed and subsoil must not be conflated. The 2018 Convention does not, in itself, assign Iran an 11- or 13-percent share. However, the manner in which the seabed and subsoil are ultimately delimited, together with subsequent agreements among the littoral states, can have major consequences for Iran’s interests.

Therefore, protecting Iran’s interests in the Caspian cannot be achieved through slogans alone. It requires a precise understanding of the historical documents, international law, geography, and the country’s economic and security interests. The Caspian is part of Iran’s history and geography, and safeguarding Iran’s rights and interests there is a historic responsibility toward both the present generation and generations to come.

This issue must not be forgotten, oversimplified, or surrendered without scrutiny. As the history of Gulistan and Turkmenchay reminds us, the rights of nations are preserved only when there is sufficient determination and capacity to understand, defend, and secure those rights.

References

1. Abdolreza Houshang Mahdavi, The History of Iran’s Foreign Relations from the Beginning of the Safavid Era to the End of the Second World War (1500–1945), Tehran: Amir Kabir Publications.

2. Ministry of Foreign Affairs of the Islamic Republic of Iran, Convention on the Legal Status of the Caspian Sea, Aktau, 12 August 2018, Persian translation.

3. Treaty of Gulistan, 1813; Treaty of Turkmenchay, 1828.

4. Treaty of Friendship between Persia and the Russian Socialist Federative Soviet Republic, Moscow, 26 February 1921, Article 11.

5. Treaty of Commerce and Navigation between Iran and the Soviet Union, 25 March 1940.

6. Convention on the Legal Status of the Caspian Sea, Aktau, 12 August 2018.

7. Firouz Mansouri, The Russian Invasion and Domination of the City of Ganja.

8. Jamshid Momtaz, “The Legal Status of the Caspian Sea,” Central Asian and Caucasus Studies Quarterly, Vol. 4, No. 10, Summer 1995, pp. 123–130.

9. Ali-Asghar Shamim, Iran during the Qajar Monarchy.