The UK government said on Wednesday that its seizure of a Russian "shadow fleet" oil tanker in the English Channel was carried out lawfully, after President Vladimir Putin threatened to "respond in kind" against Western vessels. The tanker, Smyrtos, was boarded by Royal Marine Commandos in June in a first-of-its-kind operation and remains anchored off Weymouth while investigations continue. Its captain, Ajay Pant, has been charged with breaching Russian sanctions, accused of directly or indirectly supplying or delivering prohibited Russian oil.
According to earlier reporting, the interception was a six-hour operation involving Royal Marines and the National Crime Agency, supported by the RAF, and marked the first time British forces had carried out such a boarding. Subsequent coverage confirmed that an Indian national was arrested in what officials described as a first-of-its-kind operation targeting sanctioned vessels. Pant, identified in earlier reports as master of a vessel carrying 98,000 tonnes of oil, was remanded in custody shortly after the boarding.
What did Putin say?
Putin condemned the seizure while overseeing Russian navy exercises in the Pacific Ocean, accusing Western nations of piracy against Russian shipping.
"If these plans are put into practice, we will have to respond in kind," Putin warned on Wednesday. "And not necessarily in the waters where raids on our ships and vessels are planned, but wherever we deem it necessary and appropriate, anywhere."
He further branded the boardings "nothing other than piracy and banditry" and criticised Western countries for "seizing our vessels."
How did Russian military officials respond?
Viktor Liina, commander of Russia's Pacific Fleet, accused Britain and France of running their own shadow fleets while targeting Russia's.
"We have the capacity to inspect and detain vessels of unfriendly states and their shadow fleets, and interagency cooperation is in place, ready to begin addressing these challenges," Liina said.
How has the UK justified the operation?
A government spokesperson said British armed forces and law-enforcement officers had boarded the tanker in a manner consistent with international law.
"in full accordance with international law"
The spokesperson added that the action was intended to curb the financial lifeline the sanctioned oil trade provides to Moscow.
"The UK is disrupting and deterring shadow fleet vessels and their harmful maritime activity which is fuelling Russia's war with Ukraine,"
They also drew a contrast between British and Russian conduct at sea.
"UK armed forces and commercial vessels operate firmly in line with international maritime law,"
What is the wider UK policy on shadow fleet vessels?
According to a government statement, the operation involved Royal Marine Commandos and specially trained National Crime Agency officers acting in international waters under both domestic and international law. Prime Minister Keir Starmer described the seizure as a direct blow to Russia's war economy, saying Britain would not allow those funding Putin's war effort to "hide," according to a wire service report. The same report said UK military and law-enforcement agencies had been preparing legal and operational steps to board ships that refuse to comply, or that use surveillance-evading tactics to avoid capture.
Defence Secretary John Healey had earlier said Britain was "ready" to act once training, coordination with allies, and the necessary legal groundwork had been completed, according to an earlier report. Officials had reportedly been weighing seizure plans since at least February 2026, according to a national newspaper's report on the escalating stance toward Russia's oil-export network.
How large is Russia's shadow fleet, and why does it matter?
Western nations allege Russia has built a shadow fleet to evade international sanctions imposed on its oil exports. The UK Ministry of Defence says Russia operates more than 700 such vessels, responsible for carrying 75% of the country's sanctioned oil, describing this trade as a "critical lifeline for the Kremlin" in "sustaining Russia's illegal war."
How is the EU responding to shadow fleet vessels?
Putin's remarks came as the European Union intensifies its own pressure on Russia's shadow fleet. In his address to Russian sailors, Putin singled out the EU, accusing member states of violating international maritime law and "attempting to restrict the movement of vessels belonging to our economic operators." Requests for comment on these remarks have been submitted to the EU.
Many Western countries imposed sanctions on Russian energy following the country's full-scale invasion of Ukraine in 2022. Moscow has been accused of circumventing these measures by shipping oil aboard aged tankers, often with obscure ownership or insurance arrangements. In response, the EU began sanctioning individual shadow fleet vessels in 2024 — what the European Council, the bloc's top group of national leaders, has termed "Putin's dark fleet." More than 630 vessels were under sanction as of mid-August 2026, barring them from EU ports.
Several European countries have separately been seizing or detaining Russian-linked vessels, or carrying out boardings and detentions where sanctions breaches are suspected. Most recently, the Italian navy, working alongside other EU countries, boarded a tanker in the central Mediterranean suspected of falsely flying a particular flag; that inspection did not result in seizure, though other operations have. Since the start of 2026, nine shadow fleet tankers suspected of circumventing sanctions have been seized across the EU.
What happens next?
The Smyrtos will remain held and monitored off England's south coast while investigations continue, according to the government's statement. British authorities are expected to continue examining the tanker's sanctions status and its compliance with maritime law as the case against Captain Pant proceeds.
Key Facts
- The Smyrtos was boarded by Royal Marine Commandos in June 2026 and is anchored off Weymouth.
- Captain Ajay Pant faces charges of breaching Russian sanctions.
- Putin has threatened retaliation "anywhere" against Western vessels.
- The UK Ministry of Defence says Russia's shadow fleet exceeds 700 vessels, carrying 75% of its sanctioned oil.
- More than 630 vessels are EU-sanctioned as of mid-August 2026, and nine tankers have been seized across the bloc since the start of the year.
