British Prime Minister Keir Starmer has released video footage showing a special forces operation to board and seize the Russian-linked oil tanker Smyrtos in the English Channel on Sunday.

The video shows Royal Marines commandos descending onto the vessel and conducting a search of the ship.

Ukrainian President Volodymyr Zelenskyy welcomed the operation and thanked the United Kingdom and Prime Minister Starmer for what he described as the first seizure of a Russian “shadow fleet” tanker by British authorities.

“I am grateful to the United Kingdom for this important step against Russia’s oil fleet. A tanker from the shadow fleet has been detained off the southern coast of Britain,” Zelenskyy said in a statement.

The Ukrainian leader also urged other allies to adopt legislation allowing the confiscation of oil transported by vessels linked to Russia’s shadow fleet.

The United Kingdom has previously participated in operations led by France targeting sanctioned Russian-linked tankers. Most recently, on May 31, French authorities, with British support, intercepted the tanker Tagor in the Atlantic Ocean, more than 400 nautical miles (740 kilometers) west of Brittany.

According to Prime Minister Starmer, British armed forces intercepted the tanker Smyrtos overnight in an operation that lasted approximately six hours.

The BBC reported that Royal Marines commandos and specially trained officers from the National Crime Agency boarded the vessel with support from the Royal Air Force and Royal Navy assets.

The operation involved aircraft from the Fleet Air Arm, an RAF P-8 maritime patrol aircraft, as well as the warships HMS Sutherland and HMS Ledbury.

The Smyrtos, which sails under the flag of Cameroon, is currently anchored in the English Channel, according to maritime tracking service MarineTraffic.

The UK Ministry of Defence said the operation was carried out in close coordination with France. The vessel has been detained and will remain under observation off the southern coast of England while an investigation is conducted.

British authorities stated that the enforcement action was undertaken in UK territorial waters and in accordance with both domestic and international law.

In a post on X, Starmer said the operation “deals another blow to Russia” and sends a clear message to those helping finance President Vladimir Putin’s war in Ukraine that they “will not be allowed to operate with impunity.”

Defence Minister Dan Jarvis said Russia relies on its shadow fleet to generate revenue for its military campaign in Ukraine and that the interception represents a significant disruption to those efforts.

The seizure follows a similar operation on June 1, when French authorities, supported by the United Kingdom, detained the sanctioned tanker Tagor in the Atlantic Ocean. The vessel was intercepted approximately 400 nautical miles west of the Brittany peninsula and is believed to be part of Russia’s shadow fleet used to circumvent international sanctions.