British forces boarded a sanctioned tanker suspected to be part of the Russian "shadow fleet" and detained it, Prime Minister Keir Starmer said Sunday.
The shadow fleet tankers are vessels that ship oil violating sanctions slapped over Moscow's war on Ukraine.
Moscow has threatened to rig its tankers with explosives and trigger blasts if the UK continues to attempt such actions, The Sun reported.
Royal Marine commandos rappelled from helicopters onto the vessel, the Smyrtos, in the English Channel, in what the UK's Defense Ministry called "the first U.K.-led operation of its kind," Associated Press reported.
The Smyrtos will be held and monitored off the south coast of England for a probe, according to the UK's Defense Ministry. The operation to board and detain the vessel was carried out "in close coordination" with French authorities.
France has intercepted a number of vessels linked to Russia's infamous "shadow fleet" previously.
"This operation delivers yet another blow to Russia and reminds those fueling Putin's war in Ukraine that they cannot hide," Starmer said.
The Cameroon flagged Smyrtos left the Russian Baltic port of Ust-Luga on June 5. It was headed to Port Said, Egypt, according to the MarineTraffic website.
Moscow deploys a fleet of hundreds of ships to dodge sanctions over its war against Ukraine, which began in 2022.
The development indicates an aggressive posture from Downing Street after Starmer announced on March 25 that British armed forces and law enforcement officers could board sanctioned shadow fleet vessels transiting UK waters.
The UK has argued that the aim is to close off British waters to sanctioned ships and force them onto longer, costlier routes, raising the price of moving Russian oil and tightening pressure on the Kremlin's war economy.
Some estimates put the number of vessels operating as Shadow Fleet at nearly 700. The fleet carries 75% of Russia's sanctioned oil, and feeds the Kremlin's war economy. Over 72% of shadow tankers are more than 15 years old, and there have been over 50 incidents involving Russia's shadow fleet. The UK has already sanctioned more than 500 vessels.
The latest shadow fleet operation is seen as part of a broader European effort to tighten enforcement against Russian vessels circumventing sanctions slapped for the Ukraine war. The UK has not detained any shadow fleet vessel previously, though it has backed French and US operations targeting ships suspected of breaching sanctions.
"We need to mine the tankers we use," said Dmitry Rogozin, an aide of President Vladimir Putin and a senator, The Sun reported. He urged the Kremlin to arm its shadow fleet with explosives that could be detonated if intercepted.
Rogozin said the explosives should be activated "in the event of receiving relevant commands or when the tanker deviates from its route and is forcibly diverted to a foreign port".
