Russian Cargo Ship Carrying Submarine Nuclear Reactors Sinks Off Spain in Suspected Attack
Mediterranean Sea, 12 May 2026
The Russian vessel Ursa Major mysteriously sank off Spain’s coast in December 2024 after explosions, potentially carrying nuclear reactor components destined for North Korea’s submarine programme.
The Sinking and Initial Response
The Russian cargo ship Ursa Major, also known as Sparta 3, met its fate on 23 December 2024, approximately 96 kilometres off the coast of Spain [1][2][3]. The vessel departed from St. Petersburg on 11 December 2024, carrying what was officially declared as ‘two large manhole covers,’ 129 empty shipping containers, and two large Liebherr cranes, bound for Vladivostok [1][2][3]. However, the ship’s journey took a dramatic turn when it began experiencing difficulties on 22 December 2024, with the captain reporting that the vessel suddenly slowed [2][3]. Approximately 24 hours later, three explosions occurred near the engine room on the starboard side, resulting in the deaths of Second Mechanic Nikitin and Mechanic Yakovlev [2][3][4]. Of the 16 crew members aboard, 14 were successfully rescued by Spanish authorities and taken to the port of Cartagena in Murcia, whilst two remained missing [3][4].
Nuclear Cargo Revelations
The true nature of the Ursa Major’s cargo only emerged months later through Spanish government investigations. On 23 February 2025, Spanish authorities released a statement confirming that the ship’s Russian captain, Igor Anisimov, had revealed the vessel was carrying ‘components for two nuclear reactors similar to those used in submarines’ [1][2][3]. According to the captain’s testimony, these were specifically VM-4SG-type nuclear reactors, though he remained uncertain whether they contained nuclear fuel [1][3][4]. Intelligence sources suggest these reactors were destined for North Korea’s submarine programme, with Captain Anisimov believing he was to divert to the North Korean port of Rason to deliver the sensitive cargo [1][2][3]. The ship’s owner, Oboronlogistics, had previously stated in October 2024 that their vessels were licensed to carry nuclear material [1][2], adding credibility to these revelations.
Evidence of External Attack
Physical evidence strongly suggests the Ursa Major was the victim of a deliberate attack rather than an accident. Spanish investigators discovered a 50-centimetre by 50-centimetre hole in the ship’s hull, indicating an external strike [2][3][4]. Oboronlogistics described the incident as a ‘targeted terrorist attack’ on 26 December 2024 [2][3], citing the three blasts and the precise nature of the hull damage. Spanish authorities investigated the possibility that a Barracuda supercavitating torpedo was responsible for the attack, a sophisticated weapon possessed by only a select few nations including the United States, NATO allies, Russia, and Iran [2]. However, defence analyst Plunkett from Janes suggested an alternative explanation, stating: ‘It sounds like a shaped-charge explosive that was placed against the hull by somebody or something’ [2], pointing to the possibility of a limpet mine rather than a torpedo strike.
International Response and Ongoing Investigation
The sinking triggered significant international attention, with multiple nations monitoring the situation closely. The Ursa Major had been escorted by two Russian military ships, the Ivan Gren and Aleksandr Otrakovsky, until 22 December 2024, and was tracked by Portuguese naval forces as it moved through Portuguese waters [2][3]. Following the initial explosions, the Russian escort ship Ivan Gren fired red flares, and Spain’s seismic monitoring network detected four additional explosions [3][4]. A week after the sinking, on 30 December 2024, the suspected Russian spy ship Yantar visited the wreckage site for five days and triggered four more explosions, likely in an attempt to recover or destroy sensitive equipment [1][2][3]. The United States demonstrated particular interest in the incident, deploying WC135-R ‘nuclear sniffer’ aircraft over the wreck site on two occasions: 28 August 2025 and 6 February 2026 [2][3]. The wreckage now lies at a depth of approximately 2,500 metres [3][4], making recovery operations extremely challenging and risky. Spanish lawmaker Juan Antonio Rojas Manrique reflected on the incident’s opacity, noting: ‘When someone doesn’t clearly and fully provide the information you request, you at least suspect they are hiding something… of course’ [2].