In the early hours of Sunday, Royal Marine Commandos dropped from a Chinook helicopter onto a 250-metre oil tanker in the English Channel, boarded it with KS-1 rifles, and took control without firing a shot. The vessel, the Smyrtos, was not an ordinary merchant ship—it belonged to Russia's so-called "shadow fleet," a network of tankers used to evade Western sanctions on Russian oil. This was the first UK-led operation of its kind, and it marked a significant escalation in the West's attempt to choke off the Kremlin's war funding.
So what exactly is the shadow fleet? It is a collection of mostly ageing, often poorly maintained tankers that Russia uses to transport its oil to buyers around the world, bypassing price caps and embargoes imposed by the UK, EU, and other allies. According to the Ministry of Defence, the fleet comprises about 700 vessels, and together they carry roughly 75% of Russia's sanctioned oil exports. The revenues from this oil provide a critical lifeline for the Kremlin, fuelling its war in Ukraine by paying for missiles, drones, and other military hardware.
“An explainer on Russia's shadow fleet of oil tankers and why the UK boarded one in the Channel.”
The UK has sanctioned individual shadow fleet vessels since the invasion of Ukraine began in 2022, but until now it had not physically intercepted any of them in British waters. The Smyrtos was first sanctioned in July 2025, and its detention followed a decision by Prime Minister Keir Starmer in March 2026 to authorise the use of armed forces and law enforcement to board suspect ships, in accordance with international law. The operation involved Royal Marine Commandos, officers from the National Crime Agency (NCA), aircraft from the Maritime Air Group (Chinooks, Merlin Mk4, Wildcat), an RAF P-8 patrol aircraft, and two Royal Navy ships—HMS Sutherland and HMS Ledbury. The six-hour operation was conducted overnight, and the Russian crew, who were unarmed, offered no resistance. No shots were fired and no injuries were reported.
For UK readers, this matters because the shadow fleet poses a direct threat to national security and the international rules-based order. By enabling Russia to continue earning billions of dollars from oil sales, the fleet prolongs the war in Ukraine, which has already caused global energy price spikes and economic instability. Moreover, many shadow fleet vessels are uninsured, poorly maintained, and at high risk of breaking down or causing oil spills in busy shipping lanes like the English Channel. A major spill could devastate coastal communities and wildlife. The UK's interception sends a warning to other operators: the government will not tolerate the use of British waters to circumvent sanctions. As Starmer put it, the operation “delivers yet another blow to Russia and reminds those fuelling Putin’s war in Ukraine that they cannot hide.”
Q: What is a shadow fleet? A shadow fleet is a group of tankers that Russia uses to transport its oil in defiance of Western sanctions. These vessels often change ownership, flag, or insurance to avoid detection, and they carry a large share of Russia's oil exports—around 75% according to the MoD.
Q: Why did the UK board a Russian oil tanker? The UK boarded the tanker Smyrtos because it was part of the shadow fleet and had been sanctioned in July 2025. The operation aimed to detain the vessel, investigate its activities, and send a clear message that the UK will enforce sanctions in its waters and beyond.
Q: What happens to the tanker now? The Smyrtos has been detained and will be moved to an anchorage off the south coast of England. It will be monitored for any environmental or safety concerns while investigations continue, the MoD said.
What happens next? The Smyrtos remains under UK control, and its crew are likely to face questioning by the NCA. The government has indicated it will continue to target shadow fleet vessels, and other NATO allies may follow the UK's lead in carrying out boardings. Ukrainian President Volodymyr Zelensky expressed gratitude for the operation, saying that “every decision by partners that deprives Russia of money also limits the war.” As the conflict in Ukraine grinds on, the shadow fleet will remain a key battleground in the economic war between Russia and the West.