The shadow fleet is stepping out from the shadows. The ships that have been circumventing oil sanctions for years in a reactive cat-and-mouse game with the US and Europe have changed tactics, creating unprecedented questions of international maritime law, which might have to be adjudicated in an international court.
On January 7, 2026, the US Coast Guard boarded and seized the Bella 1/Marinera oil tanker off the United Kingdom after a week-long chase that started in the Caribbean. During that chase, and to deter seizure, it went from claiming Guyana’s flag—almost certainly falsely—to being registered with Russia. That desperate change highlights a new trend in flagging behavior in the shadow fleet: notoriously and openly aligning with Russia or Iran.
Initially, the sanctions-busting oil shippers hid in traditional open registries like Panama or the Federated States of Micronesia. But with time, the US and its allies identified these vessels and sanctioned them. In early 2025, Panama bowed to pressure from the US and cracked down on the shadow fleet. Many of the de-registered ships found new homes in false registries—private companies claiming, falsely, to be the authorized operator of a country’s registry. The shadow fleet sailed on, now under obscure flags like Guyana or Sint Maarten.
But this convenient cover came at a cost: Because their flag came from an unauthorized registry, they were actually vessels without nationality. The UN Convention on the Law of the Sea (UNCLOS) and its predecessor make such vessels an exception from the general rule of exclusive flag-state control and allow warships to visit and board them. UNCLOS is silent on what comes next, but the US position for decades has been that such vessels become subject to US jurisdiction. Since 2010, several other states (e.g. France, UK, New Zealand, India) have explicitly staked out similar positions.
As Washington began to increase pressure on Venezuela, US government lawyers saw an opportunity and seized it—and a spate of oil tankers off Venezuela. In early December 2025, the US seized the Skipper, which Guyana denounced as falsely flagged, and Guyana promised further cooperation to crack down on false flagging. The shadow fleet, however, is not like traditional vessels without nationality that are engaged in human or drug smuggling—these ships are vital tools for three vulnerable, oil-dependent states. They are more effective when operating in the shadows, but if the alternative is to be seized and out of the oil trade, they would rather operate openly under the Russian, Iranian, or Venezuelan flag.
The Bella 1 was the first to embrace this logic when its crew painted the Russian flag on its hull, and its owners entered it into the Russian register in Sochi. Dozens of ships have reportedly followed suit, trading vulnerable stealth for the notoriety and protection of Russia’s flag.
The Lawfulness of the US Seizure of the Bella 1
While the rest of the shadow fleet continues to fuel Russian oil exports under the Russian flag, the Bella 1 is left behind in murky legal waters. The seizure has kicked off a vigorous debate in the law of the sea community about whether the US actions were a lawful seizure of a vessel without nationality or a violation of Russia’s right to freedom of navigation. It may fall to international courts to provide the answer.
If the US had seized the Bella 1 in the Caribbean while it claimed Guyana’s flag, it would have been an otherwise unremarkable reminder of the risks of sailing while stateless. But the formal registration with Russia before the US seized it complicates matters. International courts have given states wide leeway to establish the terms for granting ships their nationality, and the Bella 1 apparently met Russia’s terms.
For the US seizure to be lawful, then, it must find a way to invalidate the Russian nationality in this case. UNCLOS offers one such hope. Article 91 prohibits changes of nationality mid-voyage except in cases of real ownership or registration change. While the Bella 1 was clearly mid-voyage, even an on-paper change of ownership could be enough to meet the low bar set in past cases on ship nationality. Another, more tenuous hope would be to challenge the nationality by claiming that the temporary Russian registration of Bella 1, pending inspections, does not meet international standards for flag state control and thus does not confer nationality. This could, however, trip over a past ruling of the International Tribunal on the Law of the Sea (ITLOS) finding that even ships with expired registrations are not necessarily without nationality if the state otherwise claims the ship. A third, longer and more legally incoherent strategy is to argue that the US seized the vessel as a prize of war during a blockade of Venezuela. This, however, would require the US to acknowledge that it was in an international armed conflict with Venezuela, would oblige the US to bring the ship before a prize court and would complicate the US government’s attempt to refute Nicolas Maduro’s claim to prisoner of war status.
These arguments could be put to the test if Russia brings a case against the United Kingdom for aiding the US seizure. For Russia, a legal case against the UK offers mostly upside. A ruling in Russia’s favor undermines European claims to champion international law. And a ruling against Russia for changes mid-voyage creates a niche precedent that has a simple solution: don’t sail stateless. If Russia were rather to take the United States to court, that might look at first glance like a straightforward case of a violation of freedom of navigation and wrongful seizure. But ITLOS would likely find that it lacked jurisdiction over the US, which has not yet ratified UNCLOS. A case against the UK is on firmer ground as regards jurisdiction but would likely require a bit more creativity on the Russian charge.
Contending with the shadow fleet has always been a challenge for the US and its allies. As more tankers openly declare their allegiance to Russia and Iran, the shadow fleet will become more transparent. The pendulum on law enforcement against the fleet at sea will swing back from one that enables boarding and seizure, past the old status quo of flags of convenience, and into the even more insulated realm of Russian and Iranian state protection.
Continued seizures of vessels under the Russian or Iranian flag may disrupt oil flows, but they could also undermine a cornerstone of the law of the sea. In a world so dependent on sea-borne trade, this could have serious, practical consequences for US interests and prosperity if Russia, China, and others follow US precedent and embark on seizure campaigns without regard for flag state control. An alternative to seizures is for the US and its European allies to continue leveraging their unique financial power to sanction companies supporting this oil trade at sea and on shore. The US has continued this approach with Iran in recent days to pressure the regime over its crackdown on Iran’s protest movement. Sanctions are less dramatic than seizures, but they could better serve the long-term US interest in a stable international economy.
