Royal Marines

The Royal Marines are the United Kingdom's principal commando force, forming part of the Naval Service under the Royal Navy. Their core specialisms include amphibious operations, arctic warfare and maritime security operations. The Corps traces its origins to 1664 and numbers approximately 7,000 personnel organised into 3 Commando Brigade. Since 2022, Royal Marines units have been involved in training Ukrainian forces and in advisory roles supporting Ukraine's coastal defence and maritime operations.

The Smyrtos interdiction on 14 June 2026 was a qualitatively new deployment. Royal Marines rappelled from helicopters onto the Cameroon-flagged crude tanker in the English Channel, seizing a vessel suspected of carrying Russian-origin oil in breach of Western sanctions. Britain described it as the first such operation, meaning the first time Royal Marines had physically boarded and seized a Russia-linked shadow-fleet vessel. The National Crime Agency subsequently arrested an Indian national on board.

The operation drew comparisons with the long tradition of Royal Navy anti-piracy and blockade enforcement, and raised questions about the legal basis for boarding vessels in international waters under sanctions rather than piracy law. Allies noted the operation's potential to set a precedent for more aggressive physical enforcement of the Russia oil price cap across European waters.