The UK government has announced that British military forces will now have the authority to detain vessels in the country’s territorial waters that are under sanctions and are part of Russia’s “shadow fleet.”

“British military personnel will be able to board ships from the ‘shadow fleet’ transiting through UK territorial waters, as Britain increases pressure on Russian President Vladimir Putin,” the government said in a statement published on its website, as reported by the BBC.

The statement notes that this step is another blow to Russia’s “shadow fleet,” which helps finance Russia’s war against Ukraine. It was taken ahead of the summit of the Joint Expeditionary Force (JEF) in Helsinki, which opens on Thursday and will discuss regional security issues, including support for Ukraine.

Downing Street stated that the new measures will effectively close British territorial waters — including the English Channel — to sanctioned vessels, forcing them to use longer and more financially disadvantageous routes or risk being detained by Britain.

“We are living in an increasingly unstable and dangerous world, facing threats from multiple directions every day,” said British Prime Minister Keir Starmer. “Putin is rubbing his hands over the war in the Middle East, believing that rising oil prices will allow him to fill his pockets. That is why we are stepping up efforts against his ‘shadow fleet’ — not only to ensure the security of the United Kingdom, but also to deprive Putin’s war machine of the dirty revenues that fund his barbaric campaign in Ukraine.”