French authorities announced the detention of a Russia-linked oil tanker, the Tagor, in international waters of the Atlantic Ocean on Sunday morning, as part of ongoing efforts to enforce sanctions related to Russia’s 2022 invasion of Ukraine. The operation was conducted by the French Navy with assistance from the United Kingdom and other partners. French President Emmanuel Macron shared footage of commandos rappelling from a helicopter to board the vessel and emphasized the determination to prevent ships from circumventing sanctions and funding the conflict.

The Tagor was intercepted more than 740 kilometers west of Brittany, France, while transiting from the Russian port of Murmansk toward Limbe, a coastal city in Cameroon. French authorities suspect the tanker was carrying Russian or Iranian oil in violation of international sanctions. The vessel was found to be falsely flying a Cameroonian flag—a practice known as flag-hopping, commonly used by vessels in Russia’s so-called shadow fleet to evade detection and sanctions.

French prosecutors confirmed that the tanker’s captain repeatedly refused to comply with orders to stop and that the ship was diverted for further inspection following confirmation of irregularities regarding its registration and flag. A criminal investigation was launched into the failure to prove the vessel’s nationality, its absence of a valid flag, and the refusal to comply with authorities. The vessel, which had 23 crew members, is linked to Mohammad Hossein Shamkhani, a petroleum shipping magnate with reported ties to Iranian security officials, according to open-source data. French officials declined to comment further on these connections.

The Kremlin sharply criticized the seizure, with spokesman Dmitry Peskov labeling the action “illegal” and comparing it to “international piracy.” He added that Russia is taking measures to protect its cargo. Meanwhile, the Russian embassy in France stated it had requested information about the crew’s status and insisted that no formal notifications about the vessel’s detention had been received from French authorities.

The United Kingdom’s Ministry of Defence confirmed that a British helicopter from HMS Somerset supported the operation by tracking and monitoring the tanker. UK officials highlighted their commitment to clamping down on vessels linked to Russia’s shadow fleet, which has been used to circumvent sanctions and generate revenue for Moscow’s war effort. Although the UK has been outspoken about shadow fleet interdictions and increased maritime security around its waters, no sanctioned vessels have been seized by Royal Navy forces to date.

Since September, France has boarded three other vessels suspected of belonging to the shadow fleet, allowing them to sail after fines were paid. In April, France announced plans to double penalties for ships lacking valid flags or those refusing to cooperate with enforcement actions. The European Union currently sanctions nearly 600 ships believed to be part of this fleet, which regularly changes flags or uses invalid registrations to avoid detection.

President Macron underlined that such actions violate maritime law and international sanctions and contribute to funding a conflict that has now lasted more than four years. Both France and the UK have pledged to continue coordinated efforts to disrupt maritime activities that support the war in Ukraine.