Russia's New Nuke Torpedo Sub Hunts Holes In US Undersea Defenses

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.