As Russia moves closer to deploying the Poseidon nuclear torpedo aboard its dedicated Khabarovsk carrier submarine, the weapon is increasingly emerging as a test of deterrence, arms control and undersea warfare.

This month, Naval News reported that Russia is advancing the development of its Poseidon strategic underwater weapon by constructing the Khabarovsk, a purpose-built nuclear-powered submarine now undergoing fitting-out in Severodvinsk in the Russian Arctic, according to newly emerging details pieced together from satellite imagery and open-source analysis.

The submarine forms part of President Vladimir Putin’s “invincible” strategic weapons unveiled in 2018 and is designed exclusively to carry the Poseidon, a nuclear-powered, nuclear-armed intercontinental torpedo intended to evade conventional missile defenses and threaten coastal cities, strategic infrastructure and potentially carrier strike groups.

The approximately 135-meter-long Khabarovsk integrates design elements from Russia’s Borei-class ballistic missile submarines (SSBNs) and the Belgorod, the inaugural Poseidon carrier. It is believed to carry up to six Poseidon torpedoes in flooded side hangars alongside a limited conventional torpedo armament, underscoring its specialized strategic role.

The vessel is likely powered by a single OK-650V nuclear reactor derived from the improved Borei-A design and is expected to emphasize stealth and survivability as Russia invests heavily in unconventional nuclear deterrent systems.

Russia’s development of the Poseidon torpedo and its Khabarovsk carrier submarine is testing the limits of US undersea defenses while raising broader questions about deterrence, escalation stability, arms control and the future of undersea nuclear deterrence.

A September 2021 Chatham House report describes Poseidon as a large autonomous nuclear torpedo capable of speeds of around 70 knots. It states that a miniature nuclear reactor powers the weapon, giving it effectively unlimited range and allowing it to dive to depths of up to one kilometer, placing it beyond the reach of existing manned submarines.

The report says Russian officials present Poseidon as a “multipurpose” weapon capable of carrying either conventional or nuclear warheads to attack aircraft carrier groups, coastal fortifications and infrastructure targets.

As to how many Poseidon torpedoes and their dedicated submarine carriers Russia may build, Norman Polmar notes in a January 2026 article for Proceedings that Russia aims to build 30 Poseidon torpedoes to deploy on four submarines – two units for its Northern Fleet and two for its Pacific Fleet.

On possible operational scenarios, Thomas Siu notes in a January 2022 Proceedings article that Poseidon can become a semi-autonomous second-strike weapon when integrated with Russia’s Perimeter nuclear command-and-control system.

According to Siu, Perimeter ensures a second strike capability even if Russia’s nuclear command and control systems were destroyed. He notes that, through a combination of signal loss from Moscow and data from a network of seismic, radiation, and air-pressure sensors, Perimeter could send launch signals to all of Russia’s remaining nuclear weapons.

Siu notes that in the case of a nuclear attack on Russia, the Perimeter system could direct Poseidon torpedoes already on patrol in the Atlantic and Pacific to attack US port cities outside the effective range of US torpedoes that would likely be used to counter them.

This poses a challenge to US anti-submarine capabilities, as the US Navy may lack a weapon to counter such a threat since it retired the UUM-44 Subroc anti-submarine missile in 1992.

Subroc was a submarine-launched anti-submarine missile with a 55-kilometer range armed with a W-55 nuclear warhead. Fired from a standard torpedo tube, it delivered a nuclear depth charge against enemy submarines at standoff range, giving targets little warning before impact.

However, the end of the Cold War meant that Subroc – and its planned successor, Sea Lance, which was capable of carrying a conventional Mark 50 torpedo or a W89 nuclear warhead –  were canceled.

With the cancellation of Subroc and Sea Lance, the US Navy now has no long-range anti-submarine standoff weapon at its disposal – a capability gap that may even become more dangerous with the introduction of the Khabarovsk.

Looking at how Poseidon fits into Russian nuclear doctrine, an August 2025 report from the Royal United Services Institute (RUSI) positions Poseidon as part of Russia’s effort to preserve a credible second-strike nuclear capability against what it perceives as growing US counterforce and missile defense threats.

The report describes systems such as Poseidon as hedges against first-strike vulnerability amid Russian fears that US precision strike, missile defense and low-yield nuclear systems could undermine strategic stability.

It says Poseidon’s testing accelerated during the period when Russia increasingly viewed US capabilities as threatening its deterrent posture. It also portrays Poseidon as supporting Russia’s broader emphasis on ensuring survivable retaliatory forces and maintaining escalation credibility within its evolving nuclear doctrine.

Beyond compensating for Russia’s perceived first-strike vulnerability and bypassing missile defense systems, Maxim Starchak mentions in a January 2026 Carnegie Politika article that Poseidon gives Russia an asymmetric strategic advantage outside existing arms-control frameworks.

Starchak notes that Poseidon testing and deployment increase escalation risks because Russia is not obligated to notify the US of Poseidon tests, potentially keeping the US on constant alert.

Despite those strategic implications, significant questions remain about the viability of the Poseidon torpedo concept. Lukas Trakimavicius, in an October 2021 report for the NATO Energy Security Center for Excellence, contends that Poseidon’s military utility is limited by its 70-knot speed, which would take a day or more to reach an adversary’s shores from Western coastal waters.

By contrast, Trakimavicius notes that a Minuteman III intercontinental ballistic missile (ICBM) launched from the US mainland could reach strategic targets in about an hour. He also adds that increasing Poseidon’s speed would likely generate more noise, making the torpedo easier for sonar systems to detect.

However, in an August 2025 article for the peer-reviewed Space & Defense journal, July Decarpentrie notes that it is difficult to assess Poseidon’s reported capabilities with any degree of accuracy. Decarpentrie says that while some dismiss Poseidon as propaganda, most experts believe the system is genuine and heavily funded by Russia.

In these debates over Poseidon’s authenticity, she argues that the weapon’s secrecy and ambiguity, whether real or perceived, introduce uncertainty into Western threat assessments and further bolster Russia’s deterrent posture.

Whether Poseidon proves to be a transformative weapon or an expensive niche capability, its development is already reshaping deterrence calculations and forcing the US and its allies to rethink undersea nuclear competition.