The sinking of the Russian heavy-lift cargo ship Ursa Major in the western Mediterranean on 23–24 December 2024 became a Rorschach test for competing narratives: an accident at sea, an act of sabotage, or a clandestine proliferation case involving North Korea. A year later, fresh reporting in Spain has revived the story with claims that the ship was carrying nuclear-reactor components — and that the hull damage may indicate an external strike. Yet very little has been published in the form of official, citable investigative documentation.
This article separates what is verifiably established from what is attributed, alleged, or still undisclosed, drawing on contemporaneous wire reports, Spain’s public broadcaster, specialist maritime reporting, and later secondary accounts that cite Spanish investigators.
The verified timeline: distress, rescue, and sinking
Ursa Major, a 142-metre heavy-lift general cargo vessel (IMO 9538892), departed St Petersburg on 11 December 2024 with a declared destination of Vladivostok in Russia’s Far East. She was under US sanctions, as were entities linked to her ownership and operation, due to ties to Russia’s defence logistics. The ship suffered a serious casualty in international waters between Spain and Algeria, sent a distress call, and sank after a reported explosion in or near the engine room.
The distress was received off Spain’s southeast coast in heavy weather. Reuters and the Associated Press both report that the incident occurred roughly 57 nautical miles (about 105 kilometres) off Almería, and that adverse conditions complicated operations. Spanish Maritime Rescue (Salvamento Marítimo) responded and transported the survivors to Cartagena.
Crew outcomes are reported with one key uncertainty. Multiple contemporaneous reports state that 14 of the 16 crew were rescued and taken to Cartagena, while two were reported missing. Some later articles and analyses describe the two as “killed”, but no publicly available official statement confirming fatalities (as opposed to missing persons) was located in open sources used for this article. The most defensible formulation, based on contemporaneous wire reporting, remains: 14 rescued; two reported missing.
The immediate cause is described, not proven. The Russian Foreign Ministry told Reuters that the ship sank after an explosion ripped through the engine room, but the cause of that explosion was unknown at the time. Spain’s public broadcaster RTVE similarly reported that the ship suffered an explosion in the engine room and that survivors were taken to Cartagena by Salvamento Marítimo.
What is known about the ship, its operator, and the sanctions context
Ursa Major was a known heavy-lift platform with a state-linked logistics association. In open reporting, the ship is repeatedly linked to Oboronlogistika, a Russian state-linked logistics company associated with defence logistics. (Reuters, 24 Dec 2024) The Associated Press identified the ship’s owner as SK‑Yug, described as a subsidiary linked to Oboronlogistika. (AP, 24 Dec 2024)
The sanctions status is documented in US government material. A US State Department action page from May 2022 lists vessel-related designations that include “Vessel a.k.a.: Ursa Major,” reflecting the use of maritime sanctions against entities and ships connected to Russia’s war effort.
The “shadow fleet” label: what it means — and what it does not
Several later accounts, citing Spanish investigators via La Verdad, describe Ursa Major as part of Russia’s so‑called “shadow fleet”. In the sanctions context, “shadow fleet” is an umbrella term for vessels and networks used to evade controls and conceal activity through opaque ownership/management chains, flags of convenience, and deceptive practices such as AIS manipulation and complex routing. A European Parliament research brief summarises this evasion playbook in the Russian case.
It is important, however, to be precise about how Ursa Major fits — and where it differs from the archetype.
- Much of the public debate around Russia’s “shadow fleet” focuses on aging oil tankers moving crude and refined products under opaque arrangements. (Reuters, 23 Jan 2026) Ursa Major was a heavy‑lift general cargo ship, not an oil tanker.
- The vessel and linked entities were openly sanctioned and widely identifiable in mainstream reporting at the time of sinking. (The Guardian, 24 Dec 2024)
Where the “shadow fleet” frame may still be relevant is that the ship is repeatedly described as supporting state-linked logistics and operating in a sanctions environment where transparency is reduced and suspicion is heightened. That, in itself, does not prove clandestine cargo or wrongdoing — but it helps explain why investigators and analysts scrutinise routing, declarations, and post‑casualty behaviour more aggressively.
Explosion reports versus sabotage claims: what is actually evidenced
There are two distinct, publicly attributed narratives about the immediate mechanism of loss.
- “Explosion in the engine room” — This is the formulation carried in the initial Reuters report, attributed to the Russian Foreign Ministry, and repeated by a range of outlets. On its own, it describes the location of the casualty, not the cause.
- “Targeted terrorist attack” with multiple explosions — On 25 December 2024, Reuters reported that Russian state news agency RIA, citing the vessel’s owner Oboronlogistika, described the sinking as the result of three explosions and called it an “act of terrorism.” The same framing was echoed by other international outlets summarising the owner’s statement.
What is missing publicly: none of the open sources reviewed provides a published casualty investigation report, forensic imagery, or third-party technical assessment that would allow an independent conclusion about sabotage versus accident. The owner’s claim, even when carried by reputable wires, remains an attributed statement.
How maritime investigations typically narrow the cause (and why that takes time): a credible determination usually requires witness accounts, inspection of damaged machinery, material analysis of fracture patterns, and — when the wreck is accessible — underwater survey. If the wreck rests at significant depth or in unfavourable sea states, those steps can be delayed or narrowed in scope.
The cargo question: declared industrial equipment versus later allegations of nuclear components
What was declared at the time has been reported consistently. Reuters and AP stated that the ship was carrying industrial cargo, including two large port cranes and equipment described as parts for icebreakers, along with containers. (Reuters, 24 Dec 2024) This aligns with the general profile of a heavy‑lift ship and with imagery showing large deck cargo.
What changed a year later was a reported investigative assessment — not a published official report. Multiple outlets in late 2025 and early 2026, citing Spanish daily La Verdad and unnamed Spanish investigators, claimed that the ship carried undeclared components linked to two VM‑4SG naval nuclear reactors, and that the destination may have been North Korea’s port of Rason rather than Vladivostok.
The repeated elements of the allegation are unusually specific:
- the “blue‑tarped” deck loads were assessed as roughly 6–7 metres long and about 65 tonnes each;
- investigators reportedly identified coolant/steam piping and other reactor-related components in aerial imagery;
- the objects were described as covers or reactor-casing elements for the VM‑4SG, a pressurised-water reactor design used in Russia’s naval nuclear propulsion ecosystem.
Specialist maritime coverage that attributes these claims to La Verdad includes The Maritime Executive (28 Dec 2025) and Mer et Marine. A niche heavy-lift and logistics outlet carried a similar summary. (Project Cargo Journal, 2 Jan 2026)
What can responsibly be said about the VM‑4SG claim. The allegation is plausible in form — heavy-lift ships can carry large, dense modules, and non‑fuelled reactor hardware would not necessarily produce radiological signatures — but it remains unverified in open documentation. None of the sources above links to a publicly released cargo manifest, chain-of-custody imagery, or a formal investigative finding that would allow independent confirmation.
A sceptical counterpoint is therefore essential. NK News, a specialist outlet on North Korea, urged caution about the “nuke shipment” narrative, emphasising the lack of publicly verifiable evidence and the risk of over‑interpreting limited imagery and anonymous claims. (NK News, 16 Jan 2026)
Bottom line: the declared cargo is well attested in contemporaneous reporting. The VM‑4SG/reactor-component narrative is a later investigative claim attributed to Spanish investigators via La Verdad and repeated by multiple outlets — but it is not yet backed by a publicly accessible official report.
Claims of an external strike: hull damage, “torpedoes”, and what cannot be concluded
Later Spanish-media summaries, citing investigators via La Verdad, claimed that hull damage appeared consistent with perforation “from outside to inside” and floated the possibility of an external munition, including speculation about supercavitating torpedoes and a submarine intervention.
In open, citable reporting, this is the least substantiated element of the case. No mainstream contemporaneous wire report described a verified external strike; and no public technical annex, forensic imagery, or investigative report has been released that would allow independent assessment. Absent disclosed evidence, an external-strike scenario remains speculation, not an established finding.
The Yantar and the “afterstory”: what is documented and what is inferred
A recurring detail in later reporting is the appearance of the Russian oceanographic vessel Yantar in the vicinity of the wreck weeks after the sinking, with suggestions that it could conduct underwater inspection or recovery. The ship’s name is widely associated in European reporting with seabed reconnaissance and deep-sea capabilities.
Open reporting confirms only the broad idea that Yantar’s presence was noted and interpreted as linked to interest in the wreck; it does not publicly demonstrate what operations, if any, were carried out on the seabed at the Ursa Major site. Here again, the analytical boundary is straightforward: a vessel’s presence is observable; its mission is often not.
Environmental and navigational aftermath: what has been reported
Even when a ship sinks without oil-tanker volumes of hydrocarbons, authorities typically monitor for fuel sheens, debris, and hazards to navigation — especially in a busy sea lane such as the western Mediterranean.
The Associated Press reported that Spanish authorities continued to monitor the area for pollution and navigational hazards after the sinking. No open source reviewed here reports a confirmed major spill. The later “nuclear components” narrative is also accompanied, in secondary accounts, by a claim that Spanish documents assessed the cargo as non-fuelled and that no contamination was detected at the time — but, again, the underlying documents are not publicly available for verification.
What remains unknown — and the few questions that would settle most of the debate
A year on, several core questions are still unanswered in the public record:
- What exactly failed first? Was the initiating event a machinery casualty, an internal explosion, or an external impact? Public reporting offers descriptions, not proofs.
- What was the full cargo manifest and stowage plan? The declared industrial cargo is widely reported; the alleged undeclared reactor-related components are not supported by publicly released manifests or inspection records.
- Where is the wreck, at what depth, and what surveys have been conducted? Precise site data and survey results would enable a more grounded discussion of hull damage, debris fields, and environmental risk.
- What is the status of the two missing crew members? Contemporaneous reports describe two missing; subsequent claims of confirmed deaths have not been matched here with an accessible official confirmation.
- Has any coastal state or flag state published an investigative update? In the absence of a released report, the information environment will continue to favour attribution and conjecture.
