Caspian lifeline redraws the Iran–Russia war map

Aidan J. Simardone, The Cradle, May 22, 2026 —

As Washington and Tel Aviv squeeze Iran from the south, the Caspian is becoming the northern artery of a Eurasian supply network built beyond western.

The war pressure on Iran has always been mapped from the south. US bases ring the Persian Gulf, Israeli intelligence probes the region from Azerbaijan and beyond, and Washington’s naval power has long treated the narrow waterways around Iran as a pressure point. 

But the more the US–Israel axis leans on the Gulf, the more Tehran’s strategic depth shifts northward, across a closed body of water that western planners cannot easily dominate.

The Caspian Sea now matters because it gives Iran and Russia something both states urgently need, a direct, politically controlled route outside the reach of hostile land corridors. 

Overland trade must pass through states that are either aligned with Washington or unwilling to risk US secondary pressure. The Caspian, by contrast, links the two countries without a third-party gatekeeper.

Ships can still be hit by drones and missiles, but reaching them requires far deeper penetration into Iranian space and carries the danger of confrontation with Russia. In the short term, the Caspian offers Tehran a reliable supply line. Over the longer term, it could deepen Iran–Russia integration and become a central route connecting Russia to West Asia, India, and the wider world.

The legal battle over a closed sea

Is the Caspian really a sea? It’s not a trivial question. If it’s a sea, it’s subject to the UN Convention on the Law of the Sea (UNCLOS), under which territory extends 12 miles from the coastline, after which free navigation applies. If treated as a lake, the territory extends to borders mutually agreed upon by the surrounding states.

Until 1991, only two states occupied the Caspian: Iran and the USSR. In 1921, the Russo–Persian Treaty of Friendship prohibited other countries from navigating it. But when the Soviet Union fell, three new states joined the Caspian: Azerbaijan, Kazakhstan, and Turkmenistan. These former Soviet Republics disputed the 1921 treaty, insisting on negotiations that took UNCLOS into consideration. 

All the former Soviet Republics, including Russia, wanted the Caspian to be treated like a sea, but because Iran’s short coastline would give it less territory, it insisted the Caspian was a lake. The potential for UNCLOS to apply would have also allowed the entry of foreign military vessels 12 miles away from Iran. This was not a hypothetical fear, given Azerbaijan’s close alliance with Israel. Were it to host the Israeli navy, Tel Aviv could open a front in Iran’s north. 

The failure to come to a consensus made the Caspian’s legal status ambiguous, depriving the region of further integration. For instance, the proposed Trans-Caspian Pipeline would connect Turkmenistan with Azerbaijan, bringing oil and gas from Central Asia to Europe. But with no clarity on who owned the seabead, the project stalled.

In 2018, the five states came to a decision. The Caspian was not a lake or a sea, but a unique body of water that would be subject to the Convention on the Legal Status of the Caspian Sea, also known as The Caspian Sea Treaty. 

Similar to UNCLOS, states would have 15 miles of territory from the coastline and a further 10 miles for fishing. The remaining area would be shared, and any state party to the treaty could lay submarine cables and pipelines. 

But unlike UNCLOS, states not party to the treaty were prohibited from stationing their armed vessels. Iran did not secure its maximalist demand to have the Caspian classified as a lake, but the exclusion of outside militaries gave it the protection that mattered most.