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By Tom O'Connor
Deputy Editor, National Security and Foreign Policy
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As U.S. President Donald Trump meets with Israeli Prime Minister Benjamin Netanyahu and Ukrainian President Volodymyr Zelensky in Washington on Tuesday, the two foreign leaders' conflicts are joining into one major challenge for the White House.
The point of convergence is the Caspian Sea, the world's largest lake that spans some 143,000 square miles—roughly 1.5 times the combined size of North America's five Great Lakes—at a crossroads of Asia and Europe. It's an often-overlooked maritime theater, crucial for trade but not host to any major hostilities for more than 100 years.
But a century of relative calm in the Caspian has come to an end.
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First, Ukraine conducted strikes against Russian oil rigs in the Caspian Sea in December. Over the weekend, the Ukrainian military expanded operations to strike what it said were Russian commercial vessels in the sea, while Iran said one of its cargo ships was hit and a sailor killed.
But Ukraine is not the only party taking the fight to the Caspian. Israel targeted Iran's Caspian naval presence in March, weeks into the joint U.S.-Israel war launched against the Islamic Republic.
Now, Russia and Iran both vow retaliation to the latest strikes. And the world's largest lake is quickly becoming the most dangerous as two volatile conflicts intersect at the heart of Eurasia, threatening even further chaos for international trade and stability.
"Ukraine's recent strike on an Iranian vessel in the Caspian Sea should be very concerning to U.S. policymakers," Jennifer Kavanagh, senior fellow and director of military analysis at Defense Priorities, told Newsweek. "There is little evidence of Israeli-Ukrainian cooperation, but Zelensky understands that the only way he can win his war is by expanding it, dragging the United States and Europe more directly into the conflict."
"The strike on the Iranian vessel and his repeated statements about Russia sharing intelligence with Iran are transparent efforts to link the two conflicts together," Kavanagh said. "If he is a combatant in the U.S. war on Iran, he hopes the U.S. will do the same in Ukraine."
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Why the Caspian Sea's Location Matters
The Caspian Sea's shores include not only Russia to the north and Iran to the south, but also Azerbaijan to the west and Kazakhstan and Turkmenistan to the east. Russia holds the keys to the landlocked Caspian's ocean connectivity via the Volga-Don canal, which links the Caspian to the Black Sea, and has been at the center of the Russia-Ukraine war since February 2022.
Conflict is not new to the Caspian. The last major combat came during the Russian Civil War that established the foundations of the Soviet Union after World War I. A century earlier, it was a battleground for the Russian and Persian Empires.
More recently, however, the Caspian has emerged as a shared lifeline for two nations hit by international sanctions.
But Moscow and Tehran are not the only potential losers in the event that the Caspian falls to full-on conflict. Two major global trade routes count the Caspian Sea as a critical node: the International North-South Transit Corridor (INSTC) and the Trans-Caspian International Transport Route (TITR), otherwise known as the Middle Corridor.
The INSTC connects India and Iran through the Persian Gulf to land rail routes in Azerbaijan and Russia, including a cross-Caspian shipping route. The Middle Corridor, which runs East to West and is often seen as a competitor to the INSTC, depends even more heavily on the Caspian Sea, tying stops from China and Kazakhstan across Caspian waters to Azerbaijan, Georgia and Turkey, thus bypassing both Russia and Iran to reach European destinations.
The latter choice, endorsed by the U.S. and Western Europe, gained momentum in the wake of sanctions rocking Russia since 2022. But its feasibility is now under renewed scrutiny due to insecurity in the Caspian.
"In addition to its role as a conduit for arms between Iran and Russia, the Caspian also is a key node in the multimodal Middle Corridor trade route," Elizabeth Wishnick, senior research scientist at the Center for Naval Analyses and distinguished fellow at Columbia University's Weatherhead East Asian Institute, told Newsweek. "The EU and the U.S. are pinning their hopes on this route as a way of exporting strategic minerals from Central Asia, reducing China's leverage and circumventing Russia."
"For Caspian states like Kazakhstan and Azerbaijan, developing this trade route provides a welcome diversification of trade—there are many logistical obstacles already and recent security threats only add to the mix," she said.
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The global nature of the crisis is further compounded by the disruption of traffic through the Persian Gulf's crucial Strait of Hormuz chokepoint and a new campaign by the Iran-aligned Ansar Allah, also known as the Houthi movement, in the Red Sea, which serves as the gateway to the Suez Canal, forcing vessels to instead transit around South Africa.
What's become "clear," according to Wishnick, "is that the war in Ukraine doesn't stay there—it has wide ripple effects, including in the Persian Gulf, where Ukraine has seen an opportunity to share its defensive technologies for combating Iranian drones and expand its circle of supporters."
But if Washington and Kyiv's strategy is to respond to trade route disruptions by cutting off other international links, the risks could outweigh the benefits.
Ahmad Kazemi, a professor of international law and senior researcher of Eurasia in Tehran, warned this approach, as further evidenced by U.S. strikes earlier this month targeting an Iranian bridge that connected the nation to China and Russia via Central Asia, would "constitute a miscalculation and could inflict strategic losses on European and American interests."
"This is because, following the war in Ukraine and the blockage of the northern corridor from Russia to Europe, the importance of the Caspian region in supplying Europe's natural gas needs has increased dramatically," Kazemi told Newsweek. "Indeed, the Republic of Azerbaijan currently supplies gas to 16 European countries at varying rates."
"Therefore, insecurity in the Caspian Sea could not only hinder Europe's energy supply from the Caspian region but also undermine its future prospects—since Baku alone does not possess sufficient gas reserves to meet Europe's needs, and in the future Europe will require oil and gas from Turkmenistan, Uzbekistan, and Kazakhstan," Kazemi said.
He also warned, "the spread of hostilities to the Caspian region would severely weaken the security of the 'Middle Corridor' from Central Asia to the Caucasus, which is both supported by and necessary for Europe."
Bringing Russia and Iran Together
There is another way in which an effort to sever the Moscow-Tehran link could ultimately backfire.
The two countries have a history of direct security cooperation, especially in their shared support for former Syrian President Bashar al-Assad before his downfall in December 2024, and in Iran's licensing Russia's production of the infamous Shahed line of suicide drones now dominating battlefields in both Eastern Europe and the Middle East.
But their strategic partnership, formalized in an agreement that went into effect last October, does not include any mutual defense pact. This contrasts with the strategic partnership signed between Russia and North Korea in June 2024, which was followed by the latter's troops becoming directly involved in the Ukraine war.
Russia and Iran's partnership has been plagued by disappointment in the past, particularly from Tehran's side. However, the two nations have more common ground than ever, with China also heavily invested in both countries' survival.
Zelensky has already alleged that Russia was providing Iran intelligence to strike the U.S. military's Persian Gulf bases with precision as Ukraine seeks aid the Middle East's drone defense.
Alexander Cooley, political science professor at Barnard College, argued that Russia and Iran remain unlikely to pursue any formal alliance, as "both want the benefits of pragmatic partnership without entangling themselves in each other's regional wars."
"I would expect the latest developments in the Caspian to reinforce that pragmatism, with the two countries continuing to share satellite imagery and intelligence, carefully monitor northern Iranian ports, and possibly cooperate over reflagging," Cooley told Newsweek.
If destabilizing trends continue, however, Russia and Iran may be more motivated to explore new options for collaboration, potentially complicating U.S. efforts to bring an end to both wars on favorable terms.
Kazemi highlighted how even prior to the Caspian strikes, Russia and Iran's interests had met in the Caspian region. Both nations viewed with suspicion the U.S.-backed "Trump Pathway for International Peace and Welfare," to link Azerbaijan to its exclave Nakhchivan province via Armenian territory, bypassing a route proposed by Iran through its own soil.
"Therefore, Ukraine's provocative actions in the Caspian Sea—carried out as a proxy on behalf of NATO—will not only further regional convergence to punish Kyiv but will also redouble Tehran‑Moscow cooperation to strengthen Caspian security," Kazemi said. "This is because Iran and Russia are direct neighbors across the Caspian Sea, especially given that, under the 2018 Convention on the Legal Status of the Caspian Sea, the middle waters of the Caspian are considered shared/common waters."
"Consequently," he added, "Ukraine's move to extend attacks to commercial vessels in the Caspian Sea could not only usher in a new phase of military cooperation between Tehran and Moscow in this sea but also result in intensified strikes against Kyiv's interests in the Black Sea."
Kavanagh, for her part, pointed out how Russia and Iran's longstanding cooperation has already "increased over the course of the two wars," but also argued that "the support they provide each other is far less than what the United States and Europe do for Israel and Ukraine." Nor, she said, have Russia and Iran "tried to tie the two conflicts together" in such a direct manner.
"Escalation in the Caspian Sea will not, however, advance U.S. interests," Kavanagh said. "Washington can and should push Zelensky to avoid widening his war in this way."
Update 7/28/2026 2:22 p.m. ET: This article has been updated to include additional information and comments.
Contact Newsweek editors on this story: Sam Wilson and John Feng.
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