Russia’s Khabarovsk submarine may represent the cutting edge of undersea nuclear warfare, but its arrival also raises a more fundamental question: whether increasingly exotic weapons can preserve deterrence in an era when adversaries are learning to impose strategic costs without ever crossing the nuclear threshold.
This month, multiple media outlets reported that Russia has begun initial factory sea trials of its Project 09851 nuclear-powered submarine Khabarovsk, the country’s first purpose-built standard carrier for the Poseidon strategic nuclear drone system.
The submarine departed the northern shipbuilding hub of Severodvinsk to begin maritime trials, marking its first voyage since construction began in 2014, with official plans to transfer the vessel to the Pacific Fleet upon completion of testing.
Designed primarily as a second-strike retaliation platform, the Khabarovsk is equipped with six 2P39 launchers to deploy 2M39 Poseidon autonomous underwater drones—megaton-class nuclear weapons engineered to destroy coastal military facilities, critical ports, and carrier strike groups following an initial strategic exchange.
Operating at depths of approximately one kilometer and at submerged speeds of up to 200 kilometers per hour, the nuclear-powered torpedoes have an estimated 10,000-kilometer range and complex routing capabilities designed to circumvent conventional anti-torpedo defenses.
The deployment to sea represents a key milestone in Russia’s transition toward fully operationalizing its next-generation deep-sea nuclear deterrence capabilities.
In July 2022, Russia commissioned the Belgorod special mission submarine – capable of carrying four Poseidon drones and serving as the mothership for the Losharik spy submarine, which is designed to sever, tap, or inspect critical undersea cables.
The Khabarovsk appears to be more specialized as a Poseidon launch vehicle than the Belgorod, with up to four additional units planned, along with 30 Poseidon drones.
This development indicates that Russia is intensifying its focus on heavy, high-yield strategic systems as arms control norms weaken. With the expiry of the New Strategic Arms Reduction Treaty (New START) in February 2026, the Khabarovsk and Poseidon are now distinct strategic assets without effective arms control mechanisms.
They are among Russia’s “superweapons,” designed either to defeat current and emerging US missile defense systems or to serve as bargaining chips to secure US concessions in any future strategic arms negotiations.
Other such superweapons include the Sarmat super-heavy intercontinental ballistic missile (ICBM); the Avangard and Zircon hypersonic weapons; the Burevestnik nuclear-powered cruise missile; and the Kinzhal aero-ballistic missile. While Russia has used the Zircon and Kinzhal in combat against Ukraine, these weapons have not broken the stalemate in the Russia-Ukraine war.
Khabarovsk’s potential assignment within Russia’s Pacific Fleet would expand its undersea nuclear posture toward the US West Coast, Hawaii, and Japan.
However, the Khabarovsk may be entering service just as traditional notions of sea-based nuclear deterrence are being challenged. While nuclear ballistic missile submarines (SSBNs) have long been regarded as the ultimate guarantors of second-strike capability, developments in the Russia-Ukraine war increasingly question that assumption.
Ukraine’s strikes on Russian submarines in the Black Sea may call into question the survivability of Russia’s sea-based nuclear arsenal.
In December 2025, Ukraine destroyed a Russian Kilo-class submarine at its homeport in Novorossiysk, with a Sea Baby unmanned underwater vehicle (UUV) slipping past base defenses.
Previously, in September 2023, Ukraine severely damaged the Russian Kilo-class submarine Rostov-on-Don with Storm Shadow/SCALP cruise missiles while it was in drydock at Sevastopol; after repairs, Ukraine struck and sank the submarine in August 2024.
Those incidents may have prompted Russia to take countermeasures to protect its submarine fleet. For instance, The War Zone (TWZ) reported this month that Russia has begun installing anti-drone cages on the conning towers of its Kilo-class submarines assigned to the Black Sea Fleet and is keeping them submerged at port.
TWZ also reports that Russia has installed anti-drone netting over docked nuclear ballistic missile submarines (SSBNs) at the Rybachiy Naval Base in Kamchatka and deployed floating booms around submarine piers to block UUV attacks.
As those attacks show, SSBNs and special mission submarines such as the Khabarovsk and Belgorod may not be as invulnerable as previously thought.
Also, SSBNs may be “brittle” in the sense that if the submarine loses contact with higher command, is prevented from launching its nuclear payload, or is destroyed, it could result in the loss of a significant part of its operator’s nuclear arsenal.
That brittleness is not confined to SSBNs: concentrating multiple Poseidon weapons aboard a small number of Khabarovsk- and Belgorod-class submarines creates a comparable problem of force concentration.
Losing one Khabarovsk-class or Belgorod-class submarine and its entire Poseidon payload could seriously damage Russia’s nuclear posture in the Pacific, forcing it to rely more on conventional nuclear delivery systems, such as intercontinental ballistic missiles (ICBM), which may be vulnerable to US missile defenses, including the Ground-Based Midcourse Defense (GMD) or the planned Golden Dome space-based system.
While attacking a major nuclear power’s strategic assets was previously seen as a red line inviting nuclear retaliation, Ukraine’s audacious June 2025 Operation Spiderweb, which struck dozens of Russian aircraft – including several irreplaceable Tu-95 strategic bombers – may have served to call out Russia’s nuclear bluff and set a perception-breaking precedent. Instead of nuclear retaliation, Russia retaliated with a barrage of 400 drones and 40 missiles against Kyiv.
In the broader picture, nuclear-armed states may face significant difficulty deterring an adversary that employs sustained conventional and hybrid attacks – as long as the former decides not to use nuclear weapons.
Even limited use of nuclear weapons carries significant escalation risks, while leaders contemplating their use face severe domestic and international backlash – and if they proceed despite that backlash, risk infamy.
This credibility problem may deepen as new technologies expand the space for conflict below the nuclear threshold. As Alex Kolbin pointed out in a January 2026 article for the Bulletin of the Atomic Scientists, AI could soon become a strategic weapon, upending the dominant role held by nuclear weapons.
Kolbin notes that AI allows adversaries to maintain ongoing pressure through cyberattacks, information control, autonomous systems, and precision strikes, which do not trigger the same level of existential fear as nuclear retaliation.
He argues that in such an environment, nuclear weapons appear to be blunt – catastrophic, but unusable, inspiring fear but not restraint. He points out that future conflicts may be fought with tools that are cheaper, easier, and more politically acceptable to use, but cautions that such a conflict could escalate to the use of nuclear weapons.
As such, the Khabarovsk and Poseidon may ultimately prove less a revolution in nuclear deterrence than technologically sophisticated expressions of Cold War thinking, reinforcing Russia’s capacity for catastrophic retaliation even as future adversaries increasingly seek to compete, coerce and inflict strategic damage below the threshold at which such weapons can credibly be used.
