Russia may begin first sea trials of Khabarovsk nuclear submarine in 2026 as Poseidon carrier.

Russia’s Project 09851 nuclear-powered submarine Khabarovsk could begin sea trials in 2026 as construction and fitting-out activities conclude at Sevmash in Severodvinsk.

According to Izvestia, Russia’s Project 09851 nuclear-powered submarine Khabarovsk could begin sea trials in 2026 following completion of outfitting work at the Sevmash shipyard. Designed as a dedicated carrier for the Poseidon nuclear-powered unmanned underwater vehicle, the Khabarovsk was launched in November 2025 and has since entered mooring test preparations.
Follow Army Recognition on Google News at this link

Once trials and acceptance testing are completed, the Khabarovsk is expected to serve with the Pacific Fleet, potentially as part of a new submarine division based on Kamchatka. (Picture source: Sevmash)

The Project 09851 submarine was ceremonially launched on November 1, 2025, and subsequently lowered into the water on November 30, after which it entered a phase of fitting out while afloat and preparation for mooring tests. The Khabarovsk is the first submarine designed from the start as a standard carrier for the Poseidon nuclear-powered torpedo, moving beyond earlier solutions that relied on modified submarines. In Russia, the Khabarovsk is classified as a fourth-generation Project 09851 nuclear submarine intended for special missions rather than traditional patrol roles, combining characteristics associated with nuclear attack submarines and cruise-missile submarines while prioritizing the carriage of large autonomous underwater systems.

The hull design is derived from the Borei and Borei-A submarines, but omits the ballistic missile compartment, resulting in a significantly different internal arrangement optimized for mission payloads rather than SLBM launchers. Smaller than a Borei-class SSBN, the Khabarovsk nevertheless retains the endurance, propulsion, and general size associated with modern Russian nuclear submarines. Displacement figures for the Khabarovsk converge around 10,000 tonnes, with a length that is most frequently listed as 113 meters, although broader ranges extending to 135 or even 140 meters also appear, reflecting differing assessments of overall hull measurement. Beam values similarly vary, from roughly 10 meters to as much as 13.5 meters, indicating a persistent uncertainty surrounding exact external dimensions for a submarine whose detailed characteristics remain limited in public circulation.

The propulsion system is based on a nuclear power plant that allows the Khabarovsk to operate without range limitations. According to available information, it could be a pressurized-water reactor designated KTP-6-185SP with an output of about 200 MW. Power is transmitted through a turbine rated at 50,000 hp to a single shaft, driving a waterjet propulsor, with two auxiliary thrusters fitted to support maneuvering. Performance parameters consistently place underwater speed between 30 and 32 knots, while the operational diving depth is stated at up to 500 meters, situating the Khabarovsk among the higher-performance nuclear submarines in the Russian fleet in terms of mobility and depth capability.

As the Khabarovsk is associated with a Borei-derived stern configuration, it implies large vertical stabilizers combined with an X-shaped or modified cruciform control surface arrangement, rather than the classic cross-tail seen on older Soviet submarines. This configuration is said to improve hydrodynamic stability at high submerged speeds and greater control authority at depth, especially when operating a large hull with a waterjet propulsor. The vertical stabilizer integrates control surfaces and flow management around the pump-jet, supporting both directional stability and maneuverability during deep-water operations. This stern and stabilizer design choice is part of the submarine’s physical design and directly reduces cavitation and different noise profiles compared with traditional propellers.

Life and habitability aboard the submarine are designed for long deployments, with a mission duration estimated at 90 to 120 days for a crew size reported at about 100 personnel. A draft of roughly 10 meters is also cited, consistent with the submarine’s displacement and hull volume. These parameter figures reflect the need for the Khabarovsk to remain at sea for extended periods, supporting not only reactor and navigation operations but also the additional tasks linked to handling and supporting unmanned underwater vehicles during patrols, while maintaining the personnel fit for navigation, engineering, combat, and command operations.

The main reason for Russia to build the Khabarovsk is its role as a carrier for the Poseidon, with six launchers expected to be installed in the forward section of the submarine. The Poseidon, previously known as Status-6, is a nuclear-powered unmanned underwater vehicle conceived as a strategic nuclear torpedo operating independently after launch, with an operating depth of up to 1,000 meters and a reported speed of roughly 60 to 70 knots. Significantly larger than conventional torpedoes, with length estimates commonly ranging from about 16 to 24 meters, a diameter between roughly 1.5 and 2 meters, and an overall mass cited at about 100 tonnes, the Poseidon requires specially designed or modified nuclear submarines for transport and deployment. Intended to carry a nuclear warhead with a maximum yield of up to 2 megatons, its employment concept focuses on underwater detonation effects against coastal areas, naval bases, or large surface formations.

As of the most recent information, the Poseidon has not been declared fully operational. Therefore, in addition to its primary payload, the Khabarovsk is also associated with more conventional weapons to protect the submarine during transit and patrol. Systems often cited include 6 to 8 torpedo tubes of 533 mm caliber, compatible with torpedoes such as USET-80, Fizik-2, and Futlyar, as well as Kalibr missiles and naval mines. Some also mention portable air defense systems like the Igla and Verba for limited point-defense scenarios when surfaced or operating in constrained environments. Once accepted into service, Khabarovsk is expected to operate with the Pacific Fleet, potentially within a new division forming on Kamchatka, giving the fleet a dedicated submarine for Poseidon-related missions once trials and acceptance are completed. .

From a program perspective, the Khabarovsk was laid down on July 27, 2014, and experienced several schedule adjustments before its 2025 launch, with commissioning frequently associated with a 2026 timeframe following completion of trials. Order-of-battle discussions usually point to a total of three or four Project 09851 submarines in the broader program, with follow-on units potentially assigned to a related Project 09853, including a submarine named Orenburg associated with preparations for construction reportedly beginning in fall 2025 and at least one further planned hull.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.