The British armed forces intercepted a Russian shadow fleet oil tanker attempting to pass through the English Channel overnight, Sir Keir Starmer confirmed.
In a statement on X, the Prime Minister said he had "directed our Armed Forces" to "intercept" the oil tanker.
He described the operation as "successful" and "yet another blow to Russia".
Sir Keir wrote: "In the early hours of this morning, I directed our Armed Forces to intercept a shadow fleet oil tanker attempting to pass through the English Channel.
"This successful operation delivers yet another blow to Russia and reminds those fueling Putin's war in Ukraine that we will not let them hide.
"I want to thank those involved, including our Armed Forces and law enforcement officers who keep this country safe 24 hours a day, 365 days a year."
The operation took place in the early hours of this morning, the Ministry of Defence revealed, which lasted six hours.
Royal Marine Commandos and National Crime Agency agents boarded the vessel, called Smyrtos, in the Channel.
Royal Marine Commandos and National Crime Agency agents boarded the Russian oil tanker this morning
|MINISTRY OF DEFENCE
The vessel will now be held and monitored off the south coast as investigations take place.
Leader of the Opposition Kemi Badenoch backed the operation and paid tribute to those involved in the interception.
She wrote on X: "I pay tribute to the brave Royal Marine Commandos who boarded a Russian shadow fleet oil tanker overnight in the English Channel.
"Russia’s illegal war in Ukraine is funded by their oil exports in defiance of sanctions.
"As Leader of the Opposition, I support the Government in standing with Ukraine."
Newly-appointed Defence Secretary Dan Jarvis said: "Operations like this require skill, professionalism and courage. I pay tribute to our Armed Forces personnel and all those involved.
"Russia relies on its shadow fleet to fund their conflict in Ukraine and our interdiction delivers a blow to Putin’s illegal war.
The operation was supported by Chinooks, Merlin Mk4 and Wildcat helicopters; an RAF P-8 aircraft; as well as HMS Sutherland and HMS Ledbury.
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Footage from the operation shows helicopters hovering over the oil tanker in the early hours of the morning
|MINISTRY OF DEFENCE
The MoD confirmed the operation was the "first UK-led operation of its kind" after Sir Keir agreed to the military and law enforcement boarding shadow fleet vessels.
Russia's shadow fleet of oil tankers attempts to evade sanctions imposed on its exports by having obscure ownership structures.
These fleets are responsible for carrying 75 per cent of Russia's sanctioned oil, with the shadow fleet boasting over 700 vessels.
It provides a critical lifeline for Russia's war chest.
The UK has already sanctioned more than 500 of these vessels, with the MoD saying it is "working".
Russia's oil and gas revenues fell by 24 per cent year-on-year in 2025, the MoD said.
In the first quarter of 2025, vessels sanctioned by the UK reduced the amount of oil they were carrying by $1.6billion.
Earlier this week, Labour's senior defence politicians walked out en masse.
John Healey, Al Carns and Pamela Nash all resigned, citing issues with how the Government is handling defence planning and funding.
Mr Healey said in his resignation letter the Prime Minister had been "unable and the Treasury has been unwilling to commit the resources that the nation needs to defend the country at this time of rising threats".
Mr Healey's Parliamentary Private Secretary, Ms Nash, also quit and said Labour "must do better".
The UK current has 8,000 drones in its arsenal - Ukraine uses approximately 200,000 every month in the war against Russia.
Russia is capable of producing around seven million small first-person drones and eight million kamikaze attack drones every year — a total of 15 million annually.
Retired four-star general Sir Chris Deverell described the UK's drone stockpile as equivalent to "a day's worth of drones in modern conflict".
During a military training exercise in Estonia in May 2025, a British tank battalion of 17 armoured vehicles was "wiped out" in half a day by just ten Ukrainian drone operators, the Times reports.
In the army, there are only 73,000 active duty soldiers in the UK - a fraction compared to Russia's 1.3 million-strong military.
The British army is at its smallest in more than 200 years.
Mr Carns, the ex-veterans minister, accused Sir Keir of "asking our Armed Forces to operate in a more dangerous world on a budget written for a calmer one".
Air defence is also lacking in resources, with only four of the the UK's 107 Typhoon fighter jets armed and ready.
There are no missile interceptor batteries anywhere in the UK.
Russia possesses hypersonic missiles capable of striking mainland Britain, including the Oreshnik, which has a range of 3,400 miles.
Defence analysts warn that if Britain came under a sustained attack targeting multiple sites simultaneously, the country would not have the assets to defend everywhere and would be forced to choose which locations to protect and which to leave exposed.
Russia is assessed to be capable of invading a Nato partner by 2029. New satellite images show Moscow constructing barracks and warehouses on the borders of Norway, Finland, Estonia and Lithuania.
Retired vice admiral Andrew Burns said: "We are already in a state of confrontation with Russia, if not conflict."
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