LONDON (AP) — Armed British forces boarded and detained a sanctioned tanker Sunday that is suspected of being part of the Russian “shadow fleet,” shipping oil in violation of international sanctions over Moscow’s war on Ukraine, British Prime Minister Keir Starmer said Sunday.

Royal Marine commandos rappelled from helicopters onto the vessel, the Smyrtos, in the English Channel, in what the country’s Defense Ministry called “the first U.K.-led operation of its kind.”