The Ursa Major Sinking: Russian Nuclear Reactors, a North Korean Destination, and an Unclaimed Strike
A CNN investigation published this week recasts the December 2024 sinking of the Russian cargo vessel Ursa Major as something more consequential than a maritime accident off the Spanish coast. According to the report, the ship was carrying components for two submarine nuclear reactors, the destination was likely North Korea, and the sequence of events on the night of December 22 to 23, 2024 is consistent with a deliberate attack by an unidentified Western actor. None of these claims have been formally confirmed. All of them now sit on the public record.
The vessel, also operated under the name Sparta III, was owned by Oboronlogistics, a state-linked Russian shipping company that had previously confirmed its vessels were licensed to carry nuclear materials. The Ursa Major had been used in Russia’s Syria operations, including the evacuation of Russian military equipment as the Assad government collapsed. It loaded at Ust-Luga in the Gulf of Finland on December 2, transferred to a container terminal at St. Petersburg, and departed on December 11 with a declared manifest of 129 empty containers, two large Liebherr cranes, and two large objects described as “manhole covers.” Its declared destination was Vladivostok, on Russia’s Pacific coast — a routing that the Spanish investigation has openly characterized as implausible for a cargo of empty containers and cranes given the existence of the Trans-Siberian rail network.
What the captain told Spanish investigators after the sinking is the most consequential single disclosure in the public record. Under questioning at Cartagena, Captain Igor Anisimov stated that the so-called manhole covers were in fact components for two nuclear reactors of a type used in submarines, and that he was unable to confirm whether they contained nuclear fuel. The Spanish government confirmed this account in a written statement to opposition lawmakers on February 23, 2025, released only after legislative pressure. A source familiar with the Spanish investigation has separately told CNN that Anisimov believed the actual destination was the North Korean port of Rason — a routing that would never have appeared on the vessel’s official manifest.
The mechanics of the sinking are where the public record turns from disclosure into inference. Three explosions occurred on the starboard side near the engine room. Two crew members were killed. The ship listed, was abandoned, and went to the bottom. Recovery of the hull is not feasible at the recorded depth, so the physical cause of the breach cannot be examined directly. Spanish investigators have not publicly stated a finding. A source familiar with the investigation has indicated that a rare type of torpedo is one of the possibilities under consideration. Outside experts consulted by CNN have suggested a hull mine as the more likely explanation given the location and size of the damage. Either explanation requires a state actor with the access, the capability, and the operational tolerance for striking a Russian-flagged commercial vessel in international waters during the final weeks of the Biden administration.
The activity around the wreck since December 2024 is its own intelligence signal. A Russian vessel assessed to be a reconnaissance ship visited the site approximately one week after the sinking, after which four additional explosions occurred at the wreck. The most plausible interpretation is a deliberate Russian effort to destroy what remained of the cargo before any third party could recover it. Separately, US WC-135 atmospheric collection aircraft — the platform designed to sample for nuclear materials — have overflown the wreck site twice in the year since. Public flight tracking confirms the overflights. The US government has not commented on what was being measured or what was found.
The strongest piece of circumstantial corroboration for the North Korea destination did not exist at the time of the sinking. On December 25, 2025, North Korea publicly announced construction of an 8,700-ton nuclear-powered submarine and released imagery of Kim Jong Un visiting the construction site. North Korea has openly sought Russian nuclear propulsion technology as part of its expanding military relationship with Moscow, which has included the deployment of North Korean troops to the Ukrainian front. The transfer of submarine reactor technology from Russia to North Korea is the single development that would most rapidly close the gap between Pyongyang’s declared submarine program and an operational nuclear deterrent at sea. As Janes naval analyst Mike Plunkett observed to CNN, such a transfer would not be undertaken lightly and would only occur between very close allies — which is precisely the relationship Moscow and Pyongyang have spent the past two years constructing.
What remains unverified is therefore narrower than it first appears. The cargo is established as nuclear reactor components by the captain’s own statement to Spanish authorities, recorded in a Spanish government document. The implausibility of the declared destination is established by the Spanish investigation itself. The pattern of post-sinking activity by both Russia and the United States is consistent with the interpretation that the cargo’s actual nature and destination were exactly what CNN reports. What is not established — and may never be established on the public record — is the identity of the actor who put torpedoes or mines against the hull of the Ursa Major on the night of December 22, 2024, and what level of authorization that action required.
A Russian-flagged commercial vessel carrying components of a nuclear propulsion system, suspected of routing toward a sanctioned proliferator, was sunk by a third party in the Western Mediterranean. The cargo went to the seabed. The captain talked. The wreck was scrubbed. No state has claimed responsibility, and none is likely to. The most aggressive interdiction of suspected proliferation cargo since the early 2000s appears to have happened in silence, and the public will learn the rest, if at all, from defectors and declassification cycles measured in decades.