The UK armed forces have confirmed they supported a US-led operation to seize a Russian-flagged oil tanker in the North Atlantic, amid growing concerns over so-called 'shadow fleets' evading international sanctions. The tanker, Marinera, was intercepted while sailing between Iceland and Scotland after US authorities obtained a legal warrant to seize it. At Washington’s request, the UK provided surveillance support through RAF aircraft and a Royal Navy support vessel. Defence secretary John Healey said the action fully complied with international law and formed part of stepped-up efforts to counter malign activity at sea. The tanker is accused of transporting oil on behalf of Iran, Russia and Venezuela, with proceeds allegedly financing terrorism and contributing to Russia’s war in Ukraine. Moscow has condemned the seizure, while the US praised UK cooperation.