France intercepted a sanctioned Russian oil tanker suspected of being part of Russia’s so-called shadow fleet on Sunday with support from the United Kingdom, according to President Emmanuel Macron.

Operation in International Waters

French officers boarded the vessel Tagor in the Atlantic, maritime authorities stated, noting that the ship had been flying a false flag when detained about 400 nautical miles west of Brittany.

Macron emphasized that it is unacceptable for ships to bypass international sanctions, violate the law of the sea, and fund the war Russia has been waging against Ukraine. He made the statement on X, formerly known as Twitter.

A British helicopter provided support during the operation, the UK Ministry of Defence (MoD) told the BBC, the UK military has been increasingly active in tracking Russian shadow fleet operations.

Kremlin Calls Seizure ‘Illegal’

The Russian government called the seizure of the vessel “illegal” and stated it was “bordering on international piracy.” Kremlin spokesman Dmitry Peskov said Russia is taking steps to ensure the safety of its cargo.

Since launching its full-scale invasion of Ukraine in 2022, Moscow has operated a “shadow fleet” of tankers with unclear ownership structures to bypass international sanctions imposed on its oil exports. The Tagor is the fourth ship suspected of being part of this fleet that France has boarded since September 2025.

Macron said the operation, which took place in international waters, had been conducted with allies including the UK “in strict compliance with the law of the sea.”

UK Military Provides Tracking Support

According to a UK Ministry of Defence spokesperson, a helicopter on board the HMS Somerset provided “tracking and monitoring in support of the French operation.” The UK has been working alongside allies to disrupt shadow fleet operations, aiming to cut off the funding that supports Putin’s invasion of Ukraine.

“These vessels, which fail to adhere to the most basic rules of maritime navigation, also pose a threat to the environment and to everyone’s safety,” the spokesperson said.

In a video shared by Macron, armed naval officers could be seen boarding the tanker via a helicopter, the BBC has not verified the footage.

Previously, French authorities had allowed these ships to continue operating after their owners paid fines — However, they have since pledged to block them from operating.

UK Prime Minister Sir Keir Starmer announced in March he had similarly authorized the UK military to board sanctioned Russian ships; At the time, the MoD said it was “disrupting and deterring” shadow fleet vessels, though no specific details were provided.