Russia's new nuclear submarine Khabarovsk has departed Severodvinsk Port to begin sea trials in the White Sea, 140 miles from the Finnish border.
The over 10,000-ton, 135-metre vessel carries half a dozen two-megaton Poseidon nuclear torpedoes capable of triggering a radioactive tsunami large enough to plunge Britain to the depths of the ocean.
A 100-strong crew alongside a team of onshore engineers will stress-test mooring protocols, propulsion, steering, and diving capabilities, as well as the integration of sonar and onboard computing systems.
The vessel is eventually expected to travel east to join Russia's Pacific Fleet, which launched a series of missile tests last week from a disputed archipelago of islands north of Japan, triggering a major diplomatic incident.
Design and Poseidon torpedo capabilities
Named after Russian explorer Yerofey Khabarov, the Khabarovsk is a bespoke special purpose vessel in a class of its own, though its design is based on Russia's Borei-A class nuclear ballistic missile submarines that form a cornerstone of Moscow's nuclear deterrent.
The submarine is the first built with a widened bow to accommodate six Poseidon nuclear torpedoes. The only other submarine capable of launching the weapons is the RFS Belgorod, which carries three Poseidon torpedoes.
Each Poseidon torpedo measures 20 metres in length, two metres in diameter, and weighs 110 tonnes. Driven by an onboard nuclear reactor, the autonomous, manoeuvrable weapons travel underwater at speeds of roughly 70 knots at depths of 1,000 metres with an essentially unlimited range.
Conceived by Soviet engineers in the 1950s before being scrapped due to technological limitations, Poseidon torpedoes are designed to self-detonate in the water before reaching a target.
The warheads carry a yield of two megatons, more than 100 times the strength of the atomic bomb dropped on Hiroshima. Rather than relying solely on direct blast damage, the detonation triggers a radioactive tsunami.
Initial surges would drown thousands and collapse buildings, while radioactive flooding would render land within 200 miles uninhabitable for generations and cause millions of deaths. The Kremlin considers Poseidon torpedoes to be the future of its nuclear deterrent.
Strategic threats and British warnings
Dr Richard Connolly, a military expert on Russia and associate fellow at the Royal United Services Institute, described Poseidon as a "boutique capability" designed only for the "very worst of scenarios."
Russian commentators have urged the Kremlin to unleash the weapons on Britain following UK support for Ukraine, including last week's decision to share Storm Shadow cruise missile blueprints. Russian state TV presenter Vladimir Solovyov said: "Give the British three days to learn to breathe underwater, then hit them with Poseidon."
The Russian Embassy in the UK announced that the greater Britain's support for Ukraine, "the higher the price it will pay."
Admiral Lord West, former First Sea Lord and Chief of the Naval Staff, told the Daily Mail: "During the Cold War we were all over the Soviet submarine programme like a rash. But we've not been spending enough on defence, and now Putin has taken advantage of that."
Lord West added: "It is certainly worrying that the Kremlin is willing to spend a great deal of money to modernise and improve weapons systems, especially when Russia is struggling financially. It rather makes Putin look like a Bond villain."
Construction history and technical specifications
Moscow awarded a rumoured billion-dollar contract for the Khabarovsk in summer 2012 to the 125-year-old Russian submarine maker Rubin Design Bureau, with construction starting in 2014.
Originally set to be sea-worthy by 2020, severe delays meant the vessel only emerged from its construction hangar in Severodvinsk, around 600 miles north of St Petersburg, in November last year. The Covid pandemic and economic pressures from Russia's 2022 invasion of Ukraine likely contributed to the delay.
Russian President Vladimir Putin said during the submarine's rollout: "There is nothing like this in the world in terms of the speed and the depth of the movement of this vehicle, and it is unlikely there ever will be." He added there were "no ways to intercept" it.
Propulsion systems and sub-surface weaponry
The Khabarovsk has a range of around 6,200 miles, a top speed of 32 knots, and an operational depth of up to some metres. The vessel requires a crew of 100 and can remain at sea for up to 120 days.
Because Poseidon missiles are autonomous and fitted with nuclear reactors and sonar systems, the Khabarovsk does not need to be near the target of a proposed strike.
Propulsion is provided by a single-shaft pump jet that draws in water and ejects it backwards, avoiding the cavitation bubbles created by traditional propellers that generate noise detectable by enemy submarines.
When Russia released the first images of the vessel, the pump jet was covered with timber and canvas to conceal its engineering. Two additional thrusters handle low-speed manoeuvres such as docking or navigating treacherous waters.
The six Poseidon launchers are positioned in an enlarged bow, split across two flooded hangars fitted longitudinally on the port and starboard sides to fire out the front. Conventional non-nuclear torpedoes occupy the space between the two Poseidon hangars.
Russia already boasts at least 60 active submarines, and intelligence agencies understand that two further nuclear-armed vessels are under construction as part of a planned trio. Work began on the Ulyanovsk in 2017, while a third submarine, the Orenburg, has been ordered.
