In March, I wrote in Fortune that the shadow fleet exists because the rules of the sea are fundamentally voluntary. Ships can opt out. They can switch off transponders, fly flags bought from registries that never inspected anything, and carry insurance that nobody can trace. I noted that when one of them has an accident, there may be no one standing behind the policy.

That is happening now off the coast of Oman.

The vessel at the center of the incident is the Caroline Bezengi, a Suezmax built in 2001 and carrying roughly 800,000 barrels of Russian Urals crude. The ship loaded at Novorossiysk on May 11 and was bound for Sikka, in Gujarat. On June 8, an explosion flooded her engine room off southern Yemen and left her adrift. No group has claimed responsibility, and no government has announced a conclusion about the cause. Security sources and Greenpeace have both pointed to a limpet mine, but that has not been confirmed. Her crew abandoned ship three days later, and on June 30 she struck the rocks of Al Qibliyah in the Hallaniyat archipelago and grounded.

The ship now sits leaking oil inside a 667-square-kilometer marine reserve that Sultan Haitham created by royal decree nearly eight months earlier to protect an endangered population of Arabian Sea humpbacks.

Oil has reached the mainland at Ras Madrakah. Oman’s Environment Authority estimated the affected area at 390 square kilometers on August 10, while satellite analysis by SkyTruth’s John Amos suggested a figure of more than 2,000 square kilometers two days later. Dimitris Maniatis, who runs the maritime risk firm Marisks, told Bloomberg Television that cleanup alone could cost $200 million to $500 million.

Nobody is going to pay it.

The Caroline Bezengi’s last registered owner of record is Rentoor Shipmanagement Ltd, a Marshall Islands company that was dissolved on February 24. Maritime Executive reports that its Shanghai correspondence address is a dead-letter box in a residential block. The ship claimed Cameroonian registry, but Cameroon suspended its international register on February 6 after discovering that its flag was being issued through two fraudulent websites. In June, Cameroon told the IMO it had struck 39 ships from its registry. No International Group club, whose members insure roughly 87% of oceangoing tonnage, is likely to insure a ship without any approved classification. The vessel had no publicly identified insurer. That is not supposed to be possible.

So, no insurer is going to pay. Fortunately, there is a longstanding international safety net. It is not going to help.

Oman is a party to the 1992 Civil Liability Convention and the 1992 Fund Convention. It sits inside the compensation architecture the world built after Exxon Valdez and rebuilt after Prestige: strict liability on the registered owner, compulsory insurance certificates, and, as backup, the International Oil Pollution Compensation Fund, which can pay up to about $279 million per incident. The Fund is financed by levies on any company receiving more than 150,000 tonnes of oil a year in a member state.

That system worked for three decades. The Fund paid €147.9 million after the Prestige. It paid South Korea after the Hebei Spirit. In 2000, when a small tanker carrying no liability insurance and no class certificate sank off Abu Dhabi, the Funds still paid claimants in the United Arab Emirates.

It is not going to pay Oman. A spokesperson for the Fund told Reuters in August that it would not be involved in cleanup costs because the incident “was being treated as an act of war,” a category excluded by the convention. No reasoned determination has been published. The Fund’s governing bodies have not yet met on the incident. Under the convention, the burden of proving that exclusion falls on the Fund, not the claimant, and Oman has three years to force the question in court.

Meanwhile, Oman is handling shoreline response on its own dime: booms, dispersants, and crews hand-clearing some 12 kilometers of oil-sodden beach during the Khareef monsoon. For a country trying to protect a marine reserve and a coastline that is part of its tourism and fisheries economy, the spill is also a reminder that legal gaps at sea can quickly become domestic cleanup problems on land.

The larger question is what governments, especially those allied with the United States, will actually conclude. The shadow fleet has just shown its ability to impose real and immediate costs on a bystander nation. But enforcement is not politically cheap. The most likely outcome is that pollution will quietly replace sanctions as the legal basis for stopping shadow fleet vessels.

Europe spent two years interdicting on sanctions grounds and found the tool blunt. Estonia and Finland challenged more than 2,000 tankers for insurance documents by radio between 2024 and mid-2025; more than nine in 10 produced a certificate, and roughly a third of those were from sanctioned Russian or Russian-linked insurers. Increasingly, they produce certificates from Russian insurers that no government has sanctioned at all. No government has publicly disclosed how many were judged genuine.

The escalation risk is real. After Russia scrambled a Su-35 to shield a tanker Estonia tried to stop, Estonia’s navy commander told Reuters in April that the risk was “just too high” to detain shadow vessels. He named two exceptions: an imminent oil spill and damage to undersea infrastructure.

That is becoming the doctrine. Ireland passed a bill to let its Naval Service board ships and order them to cease activities threatening “the marine environment.” RUSI recommends the environmental framing explicitly, because flag states respond more readily to marine-ecosystem arguments than to sanctions enforcement. To comply with sanctions is to pick a side. Enforcing environmental regulations is entirely defensible self-interest.

Environmental regulations at sea are about to get stronger, or at least be enforced more stringently. Oman will be the example that gets cited: a nature reserve covered in floating crude oil, a cleanup bill north of $200 million, and a legal architecture that said no to helping. Oman will become a call to action for new efforts that have very little to do with saving the earth. The point is to fight the shadow fleet without publicly picking a side.

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