British Royal Marine commandos rappelled from helicopters onto a sanctioned oil tanker in the English Channel on Sunday, detaining the vessel in what the UK's Defence Ministry described as the first British-led operation of its kind against Russia's so-called shadow fleet. The six-hour operation, carried out in close coordination with French authorities, involved two Royal Navy frigates — HMS Sutherland and HMS Ledbury — as well as helicopters and a Royal Air Force anti-submarine aircraft.

The vessel, the Smyrtos, is a 243-metre tanker sailing under a Cameroon flag. It had departed from Ust-Luga, a Russian Baltic port located northeast of Estonia, on 5 June, reportedly bound for Port Said, Egypt. The ship has now been moved to an anchorage off the south coast of England, where it will be investigated for environmental and safety risks. UK authorities say the Smyrtos is suspected of being part of Russia's shadow fleet — a network of more than 700 ships used to transport sanctioned Russian oil and circumvent Western sanctions imposed over Moscow's war in Ukraine.

Prime Minister Keir Starmer hailed the operation as "another blow to Russia," warning that those financing Vladimir Putin's war in Ukraine "cannot hide." Ukrainian President Volodymyr Zelenskyy thanked Britain for its "principled resolve," adding that Russia's oil and gas revenues had helped enable the war and that every measure depriving Moscow of those funds "also limits the war itself." Zelenskyy also called on Europe to move beyond detaining ships and towards legislating for the outright confiscation of the oil they carry.

The shadow fleet is estimated to be responsible for transporting 75 per cent of Russia's sanctioned oil exports, generating revenues that, according to the UK Defence Ministry, fund the purchase of missiles and drones used against Ukrainian civilians. Britain says it has already sanctioned more than 500 Russian shadow fleet tankers, and claims that as a result, Russian oil and gas revenues fell by 24 per cent last year compared to 2024.

While France has previously intercepted shadow fleet vessels, other European countries have been slower to act. The Netherlands, for instance, has yet to move against such ships, pending new legislation — which a parliamentary majority requested last year — that would allow authorities to routinely inspect vessels suspected of sailing under false flags, escort them to anchorage, and in extreme cases seize them. Those draft laws are expected to be sent to the Dutch parliament before the summer. The UK operation marks a significant escalation in European efforts to enforce sanctions and cut off the financial lifeline sustaining Russia's military campaign.