A Russian cargo vessel, Ursa Major, which went down after a series of unexplained explosions, may have been transporting two nuclear reactor units reportedly destined for North Korea, according to a CNN report on Tuesday.
The incident, which occurred on December 23, 2024, has remained surrounded by uncertainty, with emerging findings pointing to possible covert military-related activity.
The sinking of the vessel has continued to attract scrutiny, particularly after a Spanish-led investigation suggested that military intervention may have been involved in preventing the transfer of sensitive nuclear technology. Activity near the wreck site has further fueled speculation, with U.S. nuclear “sniffer” aircraft reportedly surveying the area twice within the past year based on publicly available flight data. The ship was believed to be part of Russia’s so-called “Ghost Fleet,” a network of vessels used to evade sanctions, and was en route from St. Petersburg to Vladivostok via the Mediterranean Sea, according to its manifest.
The declared cargo listed on board included two large “manhole covers,” 129 empty shipping containers, and two Liebherr cranes. The vessel was escorted by two Russian Navy ships, identified as Ivan Gren and Aleksandr Otrakovsky, according to a statement released earlier by the Spanish Government. During the voyage, Spanish responders reportedly contacted the ship after it significantly slowed, seeking clarification on whether it was in distress. Roughly 24 hours later, the vessel deviated sharply from its route and issued a distress call.
According to the Spanish investigation, the crew reported that three explosions struck the starboard side near the engine room, resulting in the deaths of two sailors and leaving the ship disabled. Fourteen surviving crew members were later rescued by Spanish authorities. However, tensions escalated when one of the escorting Russian naval ships ordered nearby vessels to remain at least two nautical miles away and demanded the crew’s immediate transfer, a request Spanish authorities rejected in favor of continuing rescue and investigative operations.
Although the Ursa Major was initially considered stable and potentially recoverable, the situation deteriorated rapidly. At approximately 9:50 p.m., the escort ship Ivan Gren reportedly launched red flares over the area, followed by four additional explosions detected by the Spanish National Seismic Network. By 11:10 p.m., the vessel had fully sunk.
The rescued crew members were transported to the port city of Cartagena, where they were debriefed by law enforcement officials. Investigators noted that both the crew and the ship’s captain appeared reluctant to discuss details regarding the cargo and voyage. Captain Igor Vladimirovich Anisimov reportedly faced pressure to explain the term “manhole covers” listed in the manifest. As stated in the Spanish report, “He finally confessed that they were the components of two nuclear reactors similar to those used by submarines. According to his testimony and without being able to confirm it, they did not contain nuclear fuel,”.
The investigation further concluded that the items described as “manhole covers” were likely reactor hulls associated with nuclear propulsion systems, similar to those used in submarines. It also suggested that Captain Anisimov believed the vessel’s final destination could have been redirected to Rason, a port in North Korea, for delivery of the reactor components.
About a week after the incident, Russian naval ships reportedly returned to the wreck site and remained there for five days, during which four additional explosions were detected. These were believed to possibly be an attempt to destroy remaining evidence on the seabed, according to a source cited by CNN.
Interest from the United States has also drawn attention to the case. Specialized U.S. military aircraft known as “nuke sniffers,” typically based at Offutt Air Force Base, were reported to have flown over the wreck site twice—on August 28, 2025, and again on February 6, 2026. Kris Pierce, a spokesman for the base, stated that the aircraft “supports nuclear debris collection and analysis.” He added, “We cannot provide additional details regarding specific flight routing, mission findings, or any partner-related coordination,”.
Analysts cited by CNN noted that similar surveillance flights had occurred a year before the sinking, suggesting the operations may have been routine monitoring rather than incident-specific response.
Further accounts from the investigation indicate that Captain Anisimov initially claimed he did not hear any explosion when the vessel suddenly slowed on December 22. The following day, however, three explosions near the engine room killed two crew members whose bodies were never recovered. Spanish investigators suggested the attack may have involved a Barracuda supercavitating torpedo, a high-speed weapon believed to be in the possession of a limited number of states, including Russia, the United States, Iran, and select NATO members.
