Russia’s Federal Security Service (FSB) discovered several maritime magnetic mines attached to the hull of the tanker Arrhenius at the Ust-Luga port on May 25, 2026 [1, 2]. The Liberia-flagged tanker, managed by Maple Mariner Holding in the UAE, was carrying liquefied petroleum gas when the mines were found [1].
The FSB said the mines appeared to have been manufactured in a NATO country using industrially produced components. "The explosive devices resembled maritime magnetic mines and were presumably manufactured in a NATO country using industrially produced components," the agency said [2]. Russian authorities successfully deactivated the mines [1].
The FSB also noted that the installation of the mines could not have occurred in Russian territorial waters [2]. The tanker had arrived at the Ust-Luga port from Antwerp, Belgium, after reportedly remaining anchored for about a day and a half before unloading, allegedly due to a dockworkers' strike [2].
Following the incident, Russia’s Investigative Committee opened a criminal case. Charges include attempted terrorism and illegal trafficking of explosive devices related to the mines [2].
The discovery raised security concerns as the vessel was transporting liquefied petroleum gas through a key Baltic Sea port. The next development will likely involve investigations into the origin and route of the mines, as authorities continue their criminal probe.
