France has seized an oil tanker named the Grinch in the Mediterranean Sea. Authorities suspect it is part of Russia's secret "shadow fleet" that breaks Western sanctions. The French navy, aided by the UK, boarded the ship on Thursday morning between Spain and Morocco. Officials found the ship was flying a false flag and violating rules. The Grinch was traveling from Murmansk, a port in northern Russia. It was flying the flag of Comoros, but this was deemed irregular. French President Emmanuel Macron said on X, "We are determined to uphold international law and to ensure the effective enforcement of sanctions." He added, "The activities of the 'shadow fleet' contribute to financing the war of aggression against Ukraine." The UK helped by tracking the tanker with its HMS Dagger through the Straits of Gibraltar. Britain's Defence Secretary John Healy said, "Alongside our allies, we are stepping up our response to shadow vessels to choke off the funds that fuel Putin's illegal invasion of Ukraine." Ukraine’s President Volodymyr Zelensky welcomed the action, tweeting, "Exactly the kind of resolve needed to ensure that Russian oil no longer finances Russia's war." He also suggested, "Wouldn't it be fair to confiscate and sell the oil carried by these tankers?" Western countries have sanctioned Russian energy since Russia's invasion of Ukraine in 2022. This is not the first time France seized such vessels. In October, the tanker Boracay was seized and then released. Shadow fleets are widely used by Russia, Venezuela, and Iran to dodge sanctions. S&P Global estimates one in five oil tankers globally smuggle oil from sanctioned countries.