Editor’s Note: Rovshan Mammadli is a Baku-based policy analyst and journalist specializing in South Caucasus affairs and the region’s relations with the Middle East. His work has appeared in outlets including Amwaj.media, New Arab, Euractiv, Eurasianet, Caucasus Edition, and IPS-Journal. He has also published peer-reviewed research on regional security and geopolitics, most notably the article “Iran and the Second Karabakh War” by Wiley Online Library.

By Middle East Program Team

For decades, Iran’s maritime security calculations have been dominated by the Persian Gulf and the Strait of Hormuz. The Caspian Sea, by contrast, has largely occupied a secondary position. Shielded from extra-regional naval powers and geographically separated from Iran’s principal theaters of confrontation, it has generally posed fewer immediate security challenges for Tehran.

As the conflict between Iran and the U.S. continues without apparent resolution, that assumption is increasingly difficult to sustain.

The “Caspianization” of Iran’s security environment — the growing incorporation of the Caspian Sea into Tehran’s threat perceptions, military planning, and strategic connectivity calculations — is becoming an important feature of Iran’s changing security landscape. The process predates the 2026 war, but recent developments have shown how the Caspian’s growing military and economic significance can create new vulnerabilities and opportunities for Iran.

The roots of this transformation can be traced to the growing security relationship between Azerbaijan and Israel. When Azerbaijan and Israel concluded a $1.6 billion arms deal in 2012, Baku emphasized that the weapons were intended to strengthen its position against Armenia. Yet the package included Gabriel-5 anti-ship missiles, alongside Barak-8 air-defense systems, Green Pine radar, and Israeli drones. The inclusion of anti-ship missiles was particularly significant from Tehran’s perspective: Armenia is landlocked, while Iran maintains a naval presence on the Caspian. This raised the possibility that the newly acquired systems could be used against Iranian naval assets.

The development was particularly sensitive given existing Iranian-Azerbaijani tensions over Caspian maritime boundaries, offshore resources, and military activity. Israel’s expanding military relationship with Azerbaijan thus introduced a new dimension into Tehran’s threat perceptions: the possibility that its northern maritime frontier could become connected to the broader Iran-Israel conflict.

For years, however, this remained largely a potential concern. That changed in March 2026.

On March 18, Israel struck Bandar Anzali, the largest Iranian port on the Caspian Sea, marking the first reported attack on Iran’s naval infrastructure in the area. The strike hit Iranian vessels and naval facilities, including the headquarters and shipyard of the Iranian Navy’s Fourth Naval District. Subsequent strikes also targeted air-defense installations near the Caspian. Beyond the immediate military damage, the attacks underscored the exposure of Iran’s northern maritime infrastructure to a wider regional conflict.

The Caspian’s significance, however, extends well beyond military security. It has become increasingly central to economic and strategic exchanges between Iran and Russia. Since the start of the Ukraine war in 2022, Moscow and Tehran have deepened their cooperation while seeking alternative routes less exposed to Western reach and geopolitical disruptions. According to a recent report, Russia has shipped drone components, ammunition, and explosives to Iran through the Caspian to help rebuild stockpiles expended in the war against the U.S. and Israel.  

Russia has also become an important supplier of goods to Iran that would traditionally transit the Strait of Hormuz, making northern maritime routes more valuable amid the current U.S. naval blockade.

The ambitious International North-South Transport Corridor (INSTC) is central to this development. The Caspian component of the multimodal corridor connects Russian ports with northern Iranian ports, from which cargo can move through Iran toward the Persian Gulf, India, and other markets. For Tehran and Moscow, the corridor offers an alternative to established trade routes and has gained importance as sanctions and disruptions to global shipping have increased.

The Caspian is also becoming a site of competition between the INSTC and the Middle Corridor, which connects Central Asia to Europe through the South Caucasus and the Caspian. As competing connectivity projects seek a larger share of Eurasian trade, the security and reliability of the Caspian route acquire significance beyond Iran-Russia relations.

This creates a strategic paradox for Tehran: The more valuable the Caspian becomes, the more consequential its vulnerability. A maritime space that now serves military, commercial, and connectivity functions carries greater strategic costs when disruptions occur.

The July 2026 Ukrainian strike on an Iranian commercial ship illustrated this from another direction. On July 25, an Iranian vessel in the Caspian was attacked, killing one sailor and injuring another. Tehran condemned the attack, while Ukrainian President Volodymyr Zelenskyy claimed that targeted vessels were carrying military cargo to Russia. The immediate crisis was contained following an apology from Kyiv, although Tehran has continued to seek financial compensation for the fatal incident.

The episode showed that the security implications of the Caspian are no longer confined to the Iran-Israel confrontation. The Russia-Ukraine war also generates direct consequences for Iran’s northern maritime environment. This could impose new costs on Tehran, including greater investment in layered air defenses, drone monitoring, and the protection of critical ports and transport infrastructure, potentially requiring the redeployment of military personnel and equipment.

Tehran’s policy response suggests it is reassessing the Caspian’s strategic environment. Announcing plans to submit the 2018 Convention on the Legal Status of the Caspian Sea for parliamentary ratification, Deputy Foreign Minister Kazem Gharibabadi, in an interview on August 8, cited “changes in the security environment around the Caspian” among the reasons for the decision. He noted that the presence of non-littoral actors had increased significantly over the past two years, suggesting that Tehran is increasingly factoring external developments into its northern security calculations.

This raises an important question for Iran: Can the Caspian continue to serve as a reliable component of Tehran’s northern strategy when its growing economic and strategic value also makes it more exposed to external conflicts?  

The answer matters for Iran’s economic resilience as much as for its military planning. Tehran has increasingly sought connectivity with Russia, China, India, and Central Asia to reduce its vulnerability to sanctions and disruptions along its southern maritime routes. The Caspian is an important component of this strategy. Greater reliance on northern routes, however, also raises the costs of their disruption.

This does not mean that the Caspian is becoming the equivalent of the Strait of Hormuz. Tehran continues to face far greater military risks in the Persian Gulf. Nor should individual disruptions to Caspian shipping be interpreted as evidence of imminent militarization. Yet the broader trend is difficult to ignore.

The “Caspianization” of Iran’s security environment therefore reflects the convergence of three developments: the Iran-Israel confrontation, the Russia-Ukraine war, and Iran’s efforts to build alternative trade and connectivity networks. As these dynamics converge, the Caspian is becoming a critical node in Iran’s security and economic strategy — and consequently, a potential point of vulnerability.

For Tehran, protecting the Caspian may become not simply a matter of defending its northern coastline but of safeguarding an increasingly important pillar of its strategy for navigating a contested international environment.