When Insurance Markets, Not Navies, Determined Who Could Move Oil

On February 28, 2026, a joint US-Israeli operation killed Iran’s Supreme Leader Ali Khamenei at his compound in Tehran. Within hours, Iran fired missiles and drones at US bases and allied targets across at least nine countries. On March 2, two Iranian drones struck Ras Laffan Industrial City in Qatar, the largest single-site LNG export complex on Earth. QatarEnergy halted all production and declared force majeure. Nearly a fifth of global LNG supply ceased in a single day. Brent crude briefly touched $120 a barrel. It eased to $91 as positioning adjusted, then climbed back above $100 on March 12 after three more commercial vessels were struck in the Gulf.

The disruption to the Strait of Hormuz, through which a fifth of the world’s oil transits daily, was widely attributed to Iranian military action. That framing is incomplete. The mechanism that functionally sealed the strait was not military. It was contractual.

The sequence is worth understanding precisely, because it reveals where control over global energy flows actually resides.

Iran’s approach to the strait was not a blanket closure. It was conditional. On February 28, the IRGC broadcast on the international distress frequency that no ship could pass. By March 5, they narrowed the restriction: only vessels linked to the US, Israel, and their European allies were blocked. On March 10, the IRGC announced via state television that any Arab or European country expelling its US and Israeli ambassadors would receive what they described as “complete freedom and authority” to transit the strait effective the following day.

This was reported across international media. It represented a deliberate attempt to use maritime access as a diplomatic instrument, selectively punishing allied nations while incentivising defection.

The strategy had a structural vulnerability that became apparent almost immediately.

Five days before that announcement, seven of the twelve international P&I clubs (the mutual associations that collectively insure 90% of the world’s ocean-going tonnage) had issued 72-hour cancellation notices on their charterers’ liability war risk extensions for the entire Persian Gulf. By March 3, all twelve had followed. Those cancellations took effect at midnight GMT, March 5.

The implications require some context.

A large container ship is valued at approximately $200 million. Its cargo ranges from $300 million to north of $800 million depending on vessel size and route. The bank that financed the ship requires insurance as a mortgage covenant. The port that receives it requires proof of P&I and pollution liability cover. The charterer who booked it requires insurance per the charter party. International conventions, specifically the Civil Liability Convention for oil tankers and the Bunker Convention for all ships over 1,000 gross tons, mandate compulsory financial security. Port State Control can detain any vessel lacking valid certificates.

Without insurance, a vessel cannot legally operate. Not as a matter of risk appetite. As a matter of law.

When the P&I clubs withdrew war risk extensions, every commercial ship in the Gulf became an uninsurable asset. Maersk had already suspended Hormuz transits on March 1, citing crew safety. MSC ordered vessels to shelter the same day. After midnight March 5, even operators willing to accept the physical risk could not move. The contractual chain (lender, port, charterer, flag state) was broken at every link.

War risk premiums, for the limited number of underwriters still offering single-voyage policies, surged from roughly 0.2% of hull value to approximately 1%. On a $200 million vessel, that represents $2 million per transit, up from $400,000. That pricing applied to non-Western ships on peripheral routes. For direct Strait of Hormuz passage, coverage was functionally unobtainable.

The result was quantifiable. Lloyd’s List reported an 81% decline in transits on day one. NBC News cited MarineTraffic data showing tanker traffic down 90%. At the lowest point, the Joint Maritime Information Center recorded two ships passing in a 24-hour window, against a pre-crisis average exceeding 153 per day.

What followed was a form of improvisation that warrants close attention.

Vessels began broadcasting altered identity signals to transit the grey zone that Iran’s selective enforcement had inadvertently created. A Turkish LPG tanker, the Bogazici, changed its AIS transponder to “MUSLIMS VSL TURKISH” on February 28 and sailed through. On March 5, a Marshall Islands-flagged bulk carrier, the Iron Maiden, operated by Shanghai-based Cetus Maritime, broadcast “CHINA OWNER” and transited along the Omani coastline. By March 10, Windward Maritime Intelligence counted 36 vessels in the Gulf broadcasting altered nationality or crew identifiers on their AIS. Lloyd’s List reported that the Iron Maiden received no official clearance from Beijing or Tehran.

None of this reflected coordinated policy. It was decentralised risk-taking by individual operators exploiting a gap between Iran’s declared rules and the insurance market’s blanket withdrawal.

Iran’s own crude continued to flow without interruption. At least 11.7 million barrels shipped to China in the first twelve days of the conflict, tracked by TankerTrackers.com. The blockade was selective in design and porous in practice, but only for those operating outside the Western financial and legal architecture.

The attribution question matters.

A widely circulated narrative credited Lloyd’s of London with closing the strait. This is incorrect on a structural level. Lloyd’s is a marketplace where syndicates underwrite risk. It is not itself an insurer. The cancellations came from P&I clubs, member-owned mutuals such as Gard, Skuld, NorthStandard, and nine others, and from the reinsurers behind them. Lloyd’s syndicates do write an estimated 70-80% of global marine war risk specifically, but Lloyd’s holds under 10% of the world’s overall marine insurance market.

The distinction is not semantic. It matters for understanding where systemic risk concentrates.

The missiles created the physical danger. The insurance withdrawal converted that danger into a legal and financial impossibility. Iran offered conditional passage. The insurance market imposed an unconditional constraint. One mechanism was geopolitical. The other was contractual. Neither side fully controlled the outcome.

Structural observation:

The most consequential chokepoint in global energy is not ultimately governed by naval presence. It is governed by who can render the underlying commercial framework inoperable. Seven mutual insurance associations, by exercising a standard contractual clause, produced a result that Iran’s entire missile arsenal could only partially achieve.

This is not a matter of conspiracy or hidden design. It is how the infrastructure of global trade actually functions. The operative power in this crisis did not reside where conventional coverage directed attention.

As of March 12, the International Energy Agency has characterised this as the largest supply disruption in the history of the global oil market. Thirty-two IEA member countries have agreed to release 400 million barrels from emergency reserves, the largest coordinated strategic draw ever attempted. It has not been sufficient to hold prices below $100. The strait remains functionally closed. The contractual constraints remain in place.

For those managing capital across the region, the lesson is persistent: systemic risk does not always originate where it appears to. Understanding the structural architecture (legal, financial, contractual) matters at least as much as monitoring the geopolitical surface.