The United Kingdom will allow its military to board and potentially detain sanctioned Russian “shadow fleet” vessels passing through its waters, in a new step aimed at tightening pressure on Moscow’s oil exports and war financing.
The shadow fleet network of oil tankers has allowed Moscow to sustain oil export volumes by bypassing sanctions through evasive shipping practices, softening the intended economic impact and continuing to generate revenue for the state budget throughout the full-scale war in Ukraine.
Starmer announces interdiction powers
The move, announced by Prime Minister Keir Starmer’s office on March 25, gives UK Armed Forces and law enforcement the authority to interdict ships already under British sanctions as they transit areas including the English Channel. Officials said each case will be assessed individually before any operation is approved.
The decision comes as Starmer attends the Joint Expeditionary Force summit in Helsinki, where regional security and countering Russia are high on the agenda. Several partner countries, including Finland, Sweden, and Estonia, have already taken action against suspected shadow fleet vessels in the Baltic Sea.
Royal Navy has been tracking vessels and training for boarding operations
“We’re going after his shadow fleet even harder… starving Putin’s war machine of the dirty profits that fund his barbaric campaign in Ukraine,” Starmer said. He added that Russia is seeking to benefit from global instability, particularly in the Middle East, through higher oil revenues.
The UK said its navy has already been tracking these vessels and supporting allied monitoring efforts in recent weeks. Preparations have included training for boarding operations in complex scenarios, including ships that may resist or attempt to evade capture.
Russia's shadow fleet moves 75% of its crude – and has mostly sailed free
Russia’s so-called shadow fleet consists of aging and often opaque oil tankers used to bypass Western sanctions and price caps. These ships frequently operate under flags of convenience and obscure ownership structures, allowing Russian crude to continue reaching global markets despite restrictions.
British officials estimate that around 75% of Russia’s crude oil exports are transported via this network. The UK, together with its allies, has sanctioned more than 500 vessels linked to the operation.
However, enforcement of these sanctions has often been limited, allowing Russia to continue generating significant revenue through these channels even after more than four years of full-scale war. Kyiv has repeatedly urged Western partners to take a more aggressive approach, including physically interdicting vessels and tightening oversight of maritime routes.
Detained vessels face criminal proceedings
By allowing interdictions in its own waters, London aims to further disrupt these routes, forcing ships to take longer and more costly paths or risk seizure. The government said detained vessels could face legal action, including criminal proceedings against owners and operators for violating sanctions.
The step marks a further escalation in Western efforts to directly interfere with the logistics underpinning Russia’s oil exports, a key source of revenue for its ongoing war against Ukraine.
