Key Points – Russia’s Losharik (AS-31), a unique deep-diving nuclear-powered special missions submarine, is reportedly ready for sea trials in 2025 after a nearly five-year repair following a fatal 2019 fire that killed 14 crew members.
-Operated by the secretive GUGI directorate, its design, featuring seven interconnected spherical titanium hulls, allows it to operate at extreme depths (up to 19,700 feet).
-Its capabilities, including the potential to manipulate or cut vital undersea cables, are a significant concern for NATO.
-The lengthy repair process included replacing its nuclear reactor fuel, suggesting the 2019 fire was more severe than initially admitted.
Losharik’s Return: A New Submarine Threat for NATO?
Russia’s deep sea nuclear submarine, Losharik, is reportedly due to finally complete its overhaul and modernization procedures after an accident onboard in 2019 that killed 14 of its crew. It is supposedly finally prepared to conduct a series of sea trials this year.
The Losharik, also known as the AS-31 (and formerly designated as AS-12), is a Russian deep-diving nuclear-powered submarine reportedly designed and built for a variety of special missions.
These reportedly include underwater salvage, the installation of sensors and other devices on the seabed, and possibly the cutting of undersea cables.
The potential that it would be pressed into service to carry out this latter mission has become an increasing concern among US and NATO war planners due to recent incidents involving sabotage of these cables by Russian and Chinese “commercial” vessels.
The boat was launched in 2003 but was put out of commission when a fire broke out during a mission and caused the tragic death of 14 crew members, as mentioned above, with many of them being highly experienced officers.
The fire took place while the submarine was docked with its support submarine vessel, the BS-64 Podmoskovye. It is believed to have started in the battery compartment and caused very severe damage.
Lengthy Repairs
The repair process to bring the sub back up to operational status has been lengthy and complex. Among other items, it required the nuclear reactor’s fuel to be replaced, and new onboard systems were also installed to replace components from previous models.
The Russian Navy did not specify the reason for the fuel replacement. However, it appears to be inconsistent with the earlier statements by Russia’s defense ministry, which claimed that the sub was nuclear-powered but that the “nuclear elements” had been entirely isolated from the fire.
It has been an almost five-year process, and reports have been that the Losharik is ready to be placed back on operational status. Damage from the fire was extensive, but TASS had reported last year that the titanium hull of the submarine was not damaged, which now ensures the vessel’s diving capacity.
The submarine is operated by the Russian Navy’s Main Directorate for Deep Sea Research (GUGI). This is a highly secretive unit that is responsible for underwater reconnaissance and operations that are described as “crucial to Russia’s strategic interests, particularly in the Arctic and other sensitive regions.”
Unusual Design
The Losharik’s signature design feature is its spherical hull, which is key to its ability to dive to depths of 19,700 feet. The internal hull submarine is constructed from seven spherical titanium hulls. Five of these are connected together, and another two comprise the uninhabited rear sections that house the nuclear reactor and machinery.
These seven orb-like internal hulls are not visible from the outside as they are contained beneath a streamlined outer hull. It is these linked, spherical compartments that are the genesis of the submarine’s name, which originates from a character in a Russian cartoon that resembles a horse made from children’s birthday party balloons.
For reasons unknown, the process of putting Losharik back to sea following these repairs has taken months longer than anticipated. In March 2024, the Russian news agency TASS reported that an unnamed military source, described as being close to the program, claimed that “the repair of Losharik is almost complete.”
“After some remaining work, it is planned that it will go out for testing in June or July of this year,” said the same source. But this was more than a year ago.
This Titanium Submarine Can Dive Very Deep
TASS also reported last year that the titanium hull of the submarine was not damaged, which ensures the vessel’s diving capacity. The source told TASS specifically that, after its repairs, the vessel will retain its pre-accident ability to dive to 6,000 meters (19,700 ft).
After its full-scale invasion of Ukraine in 2022, President Vladimir Putin has made augmenting Russia’s military capabilities a top priority. He has made it a point of also saying Russia would continue to upgrade its nuclear forces and keep its combat readiness at the highest levels.
About the Author:
Reuben F. Johnson is a survivor of the February 2022 Russian invasion of Ukraine and is an Expert on Foreign Military Affairs with the Fundacja im. Kazimierza Pułaskiego in Warsaw. He has been a consultant to the Pentagon, several NATO governments, and the Australian government in the fields of defense technology and weapon systems design. Over the past 30 years he has resided in and reported from Russia, Ukraine, Poland, Brazil, the People’s Republic of China and Australia.
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