Russia's Khabarovsk 'doomsday' sub begins sea trials

 Russia's newest nuclear-powered submarine, the Khabarovsk, is reportedly undergoing its first factory sea trials in the White Sea after quietly departing of the Sevmash shipyard in Severodvinsk on Aug. 16. The voyage marks the first at-sea test of a submarine purpose-built to carry the Poseidon, a nuclear-powered, nuclear-armed underwater drone Moscow has branded a "doomsday" weapon.

The Khabarovsk is the lead vessel of new Project 09851 class and the first of three submarines the Russian Navy plans to build around the Poseidon strategic underwater weapon.

Its hull design is derived from the Borei-class ballistic missile submarine but is significantly shorter, having dropped the missile compartment in favor of launch bays for the giant torpedoes. Reports say the submarine can carry six.

No official word on the voyage has come from Sevmash or Russian state media.

The Barents Observer, a Norway-based outlet that has tracked the Poseidon program since first reporting on the weapon's existence in 2016, said Russian military blogs, including Military Review and Amalnews Military, reported that the submarine was at sea Aug. 16.

The Poseidon appreas to have no direct counterpart in Western arsenals.

Roughly 24 meters long, the Poseidon is said to have a range of 10,000 kilometers and a maximum operating depth of 1,000 meters, making it potentially difficult to intercept with conventional anti-submarine defenses.

Analysts describe it as a second-strike weapon designed to survive an initial nuclear exchange and strike coastal targets in the United States with a nuclear warhead, theoretically generating a radioactive tsunami.

Construction of the Khabarovsk began in July 2014, and the submarine was originally slated to enter service in 2020.

Delays that the Kremlin has never publicly explained pushed the launch to Nov. 1, 2025.

A second submarine in the class, Orenburg, is under construction. A third submarine is planned but has not been publicly confirmed to have begun construction.

The Khabarovsk is expected to join Russia's Pacific Fleet, where a dedicated Poseidon facility is being built.

The trials come against a backdrop of sharpening nuclear tensions.

Russian President Vladimir Putin announced on Oct. 29, 2025, that Russia had launched a Poseidon from a carrier submarine for the first time and activated its nuclear power plant during a test the previous day, saying, “There is nothing like this.”

Days earlier, Moscow said it had tested the nuclear-powered Burevestnik cruise missile. President Donald Trump responded on Truth Social by ordering the Department of War to begin testing U.S. nuclear weapons "on an equal basis" with Russia and China, a shift from a moratorium in place since 1992.

Whether the Khabarovsk will be fully deployed anytime soon remains uncertain.

UkrMedia, citing a May 2026 Bulletin of the Atomic Scientists assessment, reported that the Poseidon was not yet operationally deployed, noting that sea trials test the delivery platform, not the weapon's admission into service.