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On the eve of the U.S.-Israeli strikes on Iran, 56 tankers sailed through the Strait of Hormuz. Two days later, Lloyd’s List, the maritime industry’s journal of record, counted just seven tankers and a single gas carrier — all small and three of them shadow-fleet vessels — with hundreds more drifting in the Gulf of Oman. One of the world’s most important maritime chokepoints had not been mined, blockaded, or seized by a navy. Rather, it had been priced shut by a handful of drone strikes and the insurance market.

Within two days of the first U.S.-Israeli strikes on Feb. 28, major marine war-risk insurers terminated existing cover and repriced sharply upward. Tanker traffic collapsed by more than 80 percent before Iran laid a single mine. Two months on, the strait remains effectively closed. Iran briefly declared it open on April 17; within 24 hours, it shut it again. A U.S. naval blockade of Iranian ports has created a dual blockade — Iran blocking the Gulf, the United States blocking Iran. Daily transits remain in single digits. Shipowners say a return to normal is months away.

By effectively closing the Strait of Hormuz, Iran has demonstrated that a chokepoint vital for global trade can be closed with drone attacks, insurance repricing, and the self-interested logic of shipping companies. The lesson for Europe is immediate: Russia could employ the same mechanism to close key maritime chokepoints at the Danish or Turkish Straits.

Moscow has used energy as a tool of coercion against Europe since 2006 and has further escalated its use since 2014. Since the full-scale invasion of Ukraine, Russia has been running a continuous hybrid warfare campaign with the West, from targeting energy infrastructure to damaging undersea telecommunications cables. Russia does not need to blockade the Danish Straits or mine the western Black Sea to sever the continent’s liquefied natural gas supply lines and disrupt its grain trade — it only needs to make those waters uninsurable.

Three steps would sharply reduce Europe’s exposure to Russian coercion at a maritime chokepoint: a permanent war-risk monitoring cell, standby sovereign reinsurance facilities, and persistent counter-drone capabilities.

The Hormuz Model

Threats to commercial shipping at chokepoints are as old as maritime trade itself. The 1980s Tanker War spiked insurance rates in the Persian Gulf. But in every previous case, the insurance repricing followed physical damage to ships.

Hormuz inverted the sequence. Tanker traffic collapsed before a single ship was sunk because the insurers withdrew first. The closure was not a consequence of destruction but merely of the credible threat of it.

The closure mechanism operates through modern war-risk architecture. Lloyd’s Joint War Committee — the body that designates which waters count as high-risk for shipping — expanded the Hormuz zone. Under standard marine war-risk policies, insurers can cancel cover within 48 hours of such a redesignation. Shipping companies that cannot sail uninsured then self-deter.

That mechanism, not the drone itself, is what is new. And it can be triggered at a fraction of the cost of any previous chokepoint weapon.

The model is not new. The Houthis, one of Iran’s regional allies, pioneered it in the Red Sea in late 2023, forcing the world’s largest container lines — Maersk, Hapag-Lloyd, Mediterranean Shipping Company, CMA CGM, and Evergreen — and BP to suspend Red Sea transits. The rerouting of global container traffic around the Cape of Good Hope lasted for the better part of two years.

The Hormuz playbook can travel, but only with conditions. It requires a credible drone or missile capability, a geographic position sufficient to threaten maritime traffic, and the civilian insurance architecture that the globalized economy runs on.

The narrower the physical proximity between attacker and chokepoint, the lower the bar. The wider the gap, the more the attacker must invest in deniability and persistence to compensate. Iran sat on the Strait of Hormuz and its closure took 48 hours. While Russian territory does not border the Danish or Turkish Straits — meaning any closure would take longer, appear messier, and require more incidents — it could still effectively shut them down. Both sets of waters are bracketed by NATO territory and thus routine allied patrols. Consequently, the geographic bar for disruption is materially higher than at the Strait of Hormuz. But it is not insurmountable.

The Baltic Approaches

If the Hormuz model can travel, the Baltic Sea is a possible European destination.

Northern Europe’s post-2022 energy security depends on liquefied gas delivered by the sea. After Russia weaponized pipeline gas, the European Union built a new import architecture in record time. Germany added floating storage and regasification unit terminals at Wilhelmshaven and Brunsbüttel on the North Sea, and a Baltic-side terminal at Mukran on the island of Rügen, which by late 2025 had become Germany’s highest-throughput import terminal. Poland expanded Świnoujście. Lithuania commissioned Klaipėda. Finland added Inkoo, which also feeds Estonia through the Baltic connector pipeline.

The four Baltic-side terminals — Mukran, Świnoujście, Klaipėda, and Inkoo — share one geographic vulnerability. Every cargo destined for them enters the Baltic through one of three passages: the Øresund, the Great Belt, or the Little Belt. Collectively, the Danish Straits.

The geography is narrow, the trade is concentrated, and the insurance market that underwrites it is the same global system that shut down the Persian Gulf in 48 hours. Germany hedges through its North Sea terminals, and Poland partially through the Baltic Pipe from Norway.

What differs is the geopolitical context. The Danish Straits are Danish waters, ringed by NATO territory and routinely patrolled by allied air and naval forces. That changes the bar an attacker must clear. But it does not change the mechanism of closure.

NATO’s presence provides what the Strait of Hormuz lacks: allied surveillance, integrated air defense, and routine maritime patrols. A sustained drone campaign near the straits would be detected faster and attributed sooner than at the Strait of Hormuz. But detection and attribution are not prevention. The insurance market does not ask whether a navy can stop the next attack, but whether anyone can guarantee there won’t be one.

Poland’s liquefied gas supply, like that of Finland and the Baltic states, runs exclusively through the Danish Straits. A disruption there would not reroute their supply — it would sever it. Closing the Baltic approaches would punish precisely the import architecture that replaced Russian pipeline revenue after 2022.

Russia has the reach to make the threat credible, but not in the same way Iran does. Iran’s coastline abuts the Strait of Hormuz directly; Russia’s does not front the Danish (or Turkish) Straits. But the insurance-cascade model does not require direct adjacency — it requires the ability to credibly threaten shipping near the chokepoint.

What “credible threat” means here is concrete and proven. It is the documented capability to put a one-way attack munition or vessel-launched system into the relevant water at unpredictable intervals, with attribution that the Joint War Committee can read but member-state intelligence services cannot quickly close out.

A credible threat does not require sinking — it requires repetition, plausible deniability, and enough repeated incidents to convince an insurance underwriter that the next cargo is the one that gets hit.

Russia already produces Geran-2 (Shahed-type) drones — with ranges exceeding 1,300 kilometers — at industrial scale. The output is reaching 3,000 units per month at its Alabuga facility in Tatarstan. There is no open-source confirmation that these systems are currently based at Kaliningrad, Russia’s exclave on the Baltic Sea, but the range envelope from Kaliningrad and forward positions in Belarus comfortably covers the Danish Straits.

Their cheaper Gerbera variants have already reached hundreds of kilometers into NATO airspace. In July 2025, armed Gerbera drones entered Lithuanian airspace twice. One, carrying explosives, landed in a military training area. On Sept. 9–10, 19 Russian drones entered Polish airspace, triggering Article 4 consultations at NATO. Later that month, unidentified drones forced the closure of Danish airports at Copenhagen and Aalborg, directly adjacent to the Danish Straits.

Individually, these incidents may have different proximate causes. Taken together, they suggest a growing ability to probe NATO airspace and threaten infrastructure near a strategic maritime chokepoint. Russian shadow-fleet vessels operating in the western Baltic add a sea-launch vector that needs no overflight at all. Kaliningrad and the Danish Straits are roughly 700 kilometers apart. The geographic gap is not a weakness in the model. Any incoming drone or sea-launched weapon transits buffer airspace and international waters before it reaches the chokepoint.

The Strait of Hormuz did not need this architecture. Iran could fire from its own coast. The Baltic case requires it, but Russia has spent years building the components.

Russia does not need to sink a single tanker full of gas in the Kattegat — it only needs to credibly threaten one. And if the threat is delivered by an unattributed drone or a proxy actor operating from Kaliningrad or a shadow-fleet vessel, the ambiguity itself becomes the weapon.

A single strike would trigger a similar cascade to that which closed the Strait of Hormuz: Lloyd’s Joint War Committee adds the zone to its high-risk list, insurers cancel cover, and shipping companies choose not to sail. The gas that was supposed to replace Russian pipeline supply stops arriving — not because Russia cut it off, but because the market decided the transit was too expensive to insure.

The cost asymmetry is staggering. A Gerbera costs roughly $10,000 per copy. A single liquified gas cargo entering the Baltic is worth between $40 and $80 million. The insurance repricing that would follow even one successful strike would cost Northern European economies orders of magnitude more than the drone itself.

This is the same cost-exchange logic Iran exploited at the Strait of Hormuz, and one Russia already understands from its proxy experience with drone warfare in Ukraine.

The Black Sea and Turkish Straits

While the Baltic case is hypothetical, at least for now, the second European flank is not. Russia has already followed the chokepoint playbook in the Black Sea. From 2022 to 2023, Moscow weaponized the Black Sea grain corridor, allowing it to function, then choking it off, and then using its resumption as leverage. War-risk insurance premiums for Black Sea shipping spiked.

Russian naval and missile threats disrupted grain exports from Ukraine. But the commercial risk environment those threats created proved equally effective, repeatedly making western Black Sea transits difficult or uneconomic to insure.

The Turkish Straits (the Bosphorus and Dardanelles) are governed by the Montreux Convention of 1936, not United Nations Convention on the Law of the Sea transit passage. This gives Turkey sovereign control over warship transits. Turkey has restricted naval passages since 2022, limiting NATO’s ability to reinforce the Black Sea by sea.

While the legal regime is different than the Strait of Hormuz, the market mechanism is identical. If the threat environment drives insurers to reprice Black Sea transits, the effect on grain, Caspian oil, and general cargo is the same. Russia does not need to physically enter the Turkish Straits to generate closure-like effects for Black Sea commerce — it just needs to make the western Black Sea uninsurable. It has already done so once.

Ukraine demonstrated the reverse: that low-cost maritime drones can deny sea control to a conventionally stronger fleet and inflict heavy losses. Ukrainian uncrewed surface vessels sank or disabled a significant portion of the Russian Black Sea Fleet. Russian planners have had four years to study that lesson. The technology that Ukraine used to repel Russia’s fleet can deny commercial shipping — the difference is targeting, not capability. Unlike in the Baltic, Russian forces can apply it from their own coastline without any attribution gap at all.

The threat at both European flanks is well-documented and growing. In the years following Russia’s full-scale invasion of Ukraine, NATO allies invested heavily in energy diversification, ammunition stockpiles, and air defense. However, they have not yet absorbed the lesson of March 2026: that a chokepoint can be closed commercially through the rational behavior of insurers, and entirely below the threshold that triggers a collective defense response, making it a form of coercion that existing defense frameworks were not designed to counter.

Conclusion

Europe’s two maritime flanks present differing challenges. In the Black Sea, Russia operates openly from its own coastline. The threat is visible, attributable, and therefore deterrable through conventional means. In the Baltic, the threat is projected across a geographic buffer and is designed to be (im)plausibly deniable. That makes it harder for Russia to execute, but it also makes it harder for NATO to respond, because ambiguous, deniable incidents require consensus among 32 allies before the alliance can act, and the insurance cascade does not wait for consensus. The drone does not need to hit the tanker — it needs to hit the premium.

Three steps would reduce this exposure.

First, NATO’s Allied Maritime Command should establish a permanent war-risk monitoring cell with direct engagement with Lloyd’s Joint War Committee and major protection and indemnity clubs, tracking insurance repricing as a leading indicator of hybrid maritime threats. The purpose is early warning: detecting a repricing cascade before it becomes irreversible so that governments can activate countermeasures while commercial cover is still in place, as others have already argued.

Second, European governments should negotiate standby sovereign reinsurance facilities for strategic liquefied natural gas and grain cargoes, modeled on wartime trade-insurance pools. No European government has yet established such a facility, in part because the insurance-cascade threat to maritime chokepoints has not been widely recognized as a defense problem.

The coordination belongs in NATO — not the European Union alone — because the exposure spans both E.U. and non-E.U. countries. Norway supplies the gas, the United Kingdom underwrites much of the risk, and both sit outside the European Union. When commercial insurers exit, a public backstop should be ready to prevent the market from unilaterally severing energy or food supply chains.

Third, NATO should scale its existing patrol presence at the Danish Straits and western Black Sea approaches into dedicated counter-drone and mine-countermeasure postures. While routine patrols can detect, persistent postures prevent. And in the insurance market, the difference between the two is the difference between a repricing avoided and a repricing triggered.

In the Black Sea, Russia operates from its own coastline and the threat is current. In the Baltic, the threat is projected across a buffer, making forward-positioned detection and interdiction at the chokepoints the decisive factor. Both deserve the same urgency as air defense on NATO’s eastern flank.

Iran closed the Strait of Hormuz with a drone, an insurance premium, and the commercial logic of shipping companies. Russia has watched closely — it has the capability, and it has the geography. European security planners should recognize the weapon before it fires.

Miro Sedlák is an associate research fellow at the Institute for Central Europe, a senior energy sector executive, and a doctoral candidate in security and defense studies at the Armed Forces Academy of General M.R. Štefánik in Slovakia.

Image: Thomas Dahlstrøm Nielsen via Wikimedia Commons