Tehran was due to host the seventh summit of Caspian heads of state on 12 August, a meeting Moscow hoped would coincide with Iran finally ratifying the 2018 Aktau Convention on the sea's legal status.
The summit never convened, and what Tehran hosted instead, closing on 23 September, was the seventh Conference of the Parties (COP7) to the Tehran Convention, the five states’ environmental treaty. The ministerial-level meeting closed with a declaration and other decisions, and handed Iran the rotating chairmanship for two years.
Iranian officials presented the attendance of all four other Caspian littoral states' delegations as a political success, and in wartime the claim carries some weight. With its southern ports under a U.S. naval blockade, Tehran needs its northern neighbours more than ever, and on paper it has rarely been better placed with them.
Ties with Russia have grown closer under shared sanctions and war, relations with Yerevan remain warm despite Prime Minister Nikol Pashinyan's Western tilt, President Masoud Pezeshkian has worked to repair the strained relationship with Baku, and ties with Kazakhstan and Turkmenistan are cordial, if lacklustre.
Yet that goodwill has not produced agreed solutions to the questions that have divided the five since the breakup of the USSR, from the division of the seabed and the routing of pipelines to transit corridors and the role of outside powers. On several of these issues, Iran's partners have even moved in directions that may leave it more exposed.
A northern lifeline with hard limits
Iran's northern ports account for only 30 million tonnes of its 300 million tonnes of nominal port capacity, according to Ports and Maritime Organisation head Mohammad Shakibi-Nasab, yet their share of essential-goods imports has risen from 18% before the war to around 30%, while the governor of the northern province of Gilan said container arrivals into his province rose 50% year on year in the five months to 22 August.
Grains and oilseeds dominate traffic through Anzali, Amirabad and Nowshahr ports, but the Caspian Sea itself is shrinking beneath it. Iran’s Department of Environment has warned of a sharp acceleration in the Caspian’s decline in recent years, and the head of the Shipping Association of Iran has said the maximum vessel size at Iran’s northern ports has fallen from around 6,000 to 4,000 tonnes.
Land routes are congested as well, with up to 1,800 trucks queuing at the Norduz crossing with Armenia and waits of 10-15 days reported at other terminals. The crossings are also absorbing travellers, as cancelled and scarce flights push many Iranians to cross by land into Turkey and, to a lesser extent, Armenia to reach onward international connections.
Armenia and Russia, alongside Turkey, have so far remained among the few countries maintaining direct air links with Iran, but services have been repeatedly disrupted and may be suspended in coming weeks.
Of these northern partners, Russia has become the most important, and leaning on it binds Iran more tightly to another sanctioned state at war. U.S. media have reported Russian shipments of drone components, ammunition and explosives reaching Iran through the Caspian, a route Israel targeted in March with strikes on the port of Bandar Anzali. In July, Ukraine struck several vessels in the sea, including one Tehran described as an Iranian commercial ship and Kyiv said was carrying Russian military cargo.
Overall, northbound trade can absorb some imports and exports, but it cannot easily replace the scale and infrastructure of Iran's southern ports, particularly for the country's major hard-currency exports that are clustered in its southern provinces.
An unratified sea
Iran is the last of the five littoral states yet to ratify the Aktau Convention, which cannot enter into force without it. The cabinet approved a ratification bill in July and sent it to parliament, after Russian Foreign Minister Sergei Lavrov said in December 2025 that Moscow wanted the process completed before the Tehran summit.
Opposition in parliament remains strong to a text seen as surrendering Iranian leverage at a time of crisis, with lawmakers arguing that it should not be approved until Iran's share of the sea is settled in its favour.
That share is a central grievance. Tehran has long argued for an equal 20%, while estimates based on coastline length put its potential share at roughly 9-13%. The convention itself fixes no percentage division of the seabed. Instead, Article 8 leaves seabed and subsoil boundaries to agreements between neighbouring states, while the method for straight baselines is to be determined through a separate five-party agreement.
Current and former Iranian diplomats argue that this makes the text more favourable to Iran than its critics suggest. Hardliners, however, accuse the foreign ministry of trading away national interests to placate neighbours deemed untrustworthy.
In fact, distrust shapes the debate, and much of it is directed at Iran’s own negotiators. Critics point to two precedents, the first being Tehran’s 2018 agreement to develop the disputed Alborz oil structure jointly with Azerbaijan on a 50-50 basis, which they say conceded half a field Iran had claimed in full. The second is the withdrawal of Iran’s drilling rig from the deepwater Sardar Jangal field, which Baku also contests, a move they argue cost Iran a physical presence that could have anchored its baseline claims.
Security is the second fault line. Article 3 bars non-littoral armed forces from the Caspian, which Tehran presents as a key gain, but Iranian analysts warn of indirect presence, for instance Israeli-linked vessels operating under the Azerbaijani flag, given Baku's close defence ties with Israel. For Tehran, the risk is less a foreign navy on the sea than outside powers gaining a foothold through its neighbours.
The pipeline that bypasses Iran
The Iran war's impact on global energy markets has also revived the Trans-Caspian Gas Pipeline, a proposed subsea line that would carry Turkmen gas to Azerbaijan and on to Turkey and Europe through the Southern Gas Corridor, with Turkey calling for renewed talks in April.
Article 14 of the Aktau Convention provides that a pipeline route requires the agreement of the state whose seabed sector it crosses, rather than the consent of all five littoral states. Iranian ratification would therefore remove one potential legal obstacle to the project, although environmental procedures, unresolved seabed boundaries and questions over Turkmen volumes, financing, and European offtake contracts would remain.
The pipeline’s appeal lies partly in Iran’s own isolation and U.S. sanctions. A 2025 arrangement to swap Turkmen gas through Iran to Turkey collapsed after a few months, when Washington extended sanctions to gas barter trades. More recently, Iran’s 25-year gas supply contract with Turkey expired on 29 July without a publicly announced renewal, although gas may continue to flow under a make-up clause. Ankara, which has been diversifying towards LNG, has little incentive to deepen its reliance on Iranian supply under these conditions.
