A Russian cargo ship carrying what its captain described as nuclear reactor components sank under mysterious circumstances off the coast of Spain in December 2024 – and new details suggest Moscow may have been secretly shipping sensitive military cargo to North Korea.”
The vessel, Ursa Major, also known as Sparta 3, sank on Dec. 23, 2024, around 60 miles off the coast of Spain. The ship’s fate remained largely undisclosed for months, but CNN reported that the incident may have involved sensitive military cargo linked to Russia’s defense sector and possibly North Korea.
According to the investigation, the vessel departed Russia shortly after North Korean leader Kim Jong Un sent troops to support Moscow’s war against Ukraine. The ship had previously been involved in Russia’s military operations in Syria and was reportedly used to evacuate Russian military equipment.
The ship docked in the Russian port of Ust-Luga on Dec. 2 before moving to a container terminal in St. Petersburg. Public shipping records listed its destination as Vladivostok in Russia’s Far East and described the cargo as two large “manhole covers,” 129 empty shipping containers, and two large Liebherr cranes.
The Spanish government later confirmed that the Russian captain told investigators the vessel was carrying “components for two nuclear reactors similar to those used in submarines.” The captain said he could not confirm whether the cargo contained nuclear fuel, according to the government statement cited by CNN.
CNN also reported that the ship’s owner, state-linked company Oboronlogistics, announced in October 2024 that its vessels had been licensed to transport nuclear materials. Video footage reviewed by CNN reportedly showed containers being loaded into the hull with empty space left beneath the structures later identified as “manhole covers.”
The vessel traveled down Europe’s Atlantic coast while being monitored by Portuguese naval forces. According to the Portuguese Navy, two Russian military ships — the Ivan Gren and Aleksandr Otrakovsky — escorted the cargo ship during part of the voyage.
On Dec. 22, after Portuguese forces stopped tracking the vessel, the Ursa Major reportedly slowed dramatically in Spanish waters, prompting Spanish rescue authorities to contact the crew. The crew initially responded that there was no emergency.
Roughly 24 hours later, however, the vessel abruptly changed course and issued a distress signal after suffering three explosions on its starboard side near the engine room, according to the Spanish investigation cited by CNN. Two crew members were killed in the blasts.
The surviving 14 crew members evacuated by lifeboat and were rescued by a Spanish rescue vessel. Video reviewed by CNN showed the ship listing heavily but still afloat after the initial explosions.
Spanish rescue teams boarded the vessel and searched for survivors. According to CNN, rescuers found the engine room sealed and inspected containers that reportedly contained trash, fishing nets, and miscellaneous equipment. A source familiar with the investigation told CNN the vessel initially appeared stable and unlikely to sink immediately.
Later that evening, however, additional explosions reportedly occurred near the vessel after the Russian military ship Ivan Gren ordered nearby ships to keep their distance. CNN reported that Spain’s National Seismic Network detected four seismic signatures at approximately the same time, patterns which officials said resembled underwater explosions or blasts.
By late evening, the Ursa Major had sunk.
CNN reported that the Russian captain, identified as Igor Anisimov, later told investigators he believed the vessel may ultimately have been redirected to the North Korean port of Rason. Spanish investigators questioned why a ship would take a lengthy maritime route carrying only cranes, empty containers, and the large unidentified cargo, given that Russia possesses an extensive rail network connecting the country from west to east. The report suggested the cranes may have been intended to help unload sensitive cargo upon arrival.
The incident has drawn additional attention due to unusual military activity around the wreck site. According to publicly available flight data cited by CNN, US WC135-R aircraft – commonly used to detect radioactive contamination and collect nuclear-related atmospheric data – flew over the wreck area twice following the sinking.
A spokesperson for the US Air Force’s 55th Wing confirmed the aircraft’s mission typically supports “nuclear debris collection and analysis” but declined to comment on specific operations or findings.
The Spanish government has stated that the wreck lies approximately 2,500 meters (1.5 miles) below the surface and that recovering the ship’s data recorder would involve significant technical risks. Spanish authorities have reported no evidence of radioactive contamination along the country’s southern coast.