When Russia launched its latest nuclear submarine the Khabarovsk last month from the Arctic port of Severodvinsk, it caused a stir in defence circles.
While the new “doomsday” Poseidon nuclear torpedoes are theoretically capable of unleashing a radioactive tsunami, submarine specialists have also focused on its advanced noise-proofing technology.
New pump-jet propulsion, composite hull coatings and improved reactor coolant pumps in recent decades have sharply reduced the acoustic signatures on Russian nuclear submarines to the point where they are nearly inaudible.
The Khabarovsk is able to slip through the world’s oceans largely undetected — a serious threat not only to shipping lanes but to Europe’s vast network of undersea infrastructure.
That is the main future challenge faced by the Royal Navy, which has laid plans for a new generation of sensor technology to be unveiled by Britain’s Ministry of Defence on Monday.
Officials said the strategy was a “direct response to a resurgence in Russian submarine and underwater activity”, including the movements of the Russian “research” vessel Yantar, believed by western intelligence agencies to map and potentially tamper with undersea pipelines or cables.
Known collectively as Atlantic Bastion, it involves using advanced Type 26 anti-submarine frigates, P-8 Poseidon aircraft and newer autonomous sea drones fitted with acoustic sensors aimed at keeping British and Irish waters free of enemy submarines.
Defence secretary John Healey, visiting HM Naval Base Portsmouth last week to unveil the initial work, called Atlantic Bastion “a blueprint for the future of the Royal Navy”.
“It combines the latest autonomous and AI technologies with world-class warships and aircraft to create a highly advanced hybrid fighting force,” he said.
At the heart of the concept — and the first part phase to go in the water early next year — is Atlantic Net: a grid of sensors that will use fleets of autonomous underwater gliders to detect, classify and track hostile submarines.
One person with knowledge of Atlantic Net said it would focus on the Greenland-Iceland-UK (GIUK) gap — the maritime choke point that has formed Britain’s first line of defence in the north Atlantic for nearly a century.
The idea is reminiscent of the Sound Surveillance System (SOSUS), the cold war network of secret hydrophones that once listened for Soviet submarines.
While SOSUS relied on fixed arrays, the new system depends on mobile, AI-guided platforms able to patrol vast areas of ocean autonomously.
The first contracts, unambitious in scale at around £4mn, are due to be awarded before Christmas.
But MoD officials expect the programme to expand quickly. One official familiar with early planning said tens of millions yearly would eventually be spent.
Britain’s maritime guardianship of the north Atlantic predates Nato itself.
The Royal Navy was patrolling the GIUK gap as far back as the sinking of the Bismarck, which traversed the passage on its ill-fated breakout in 1941.
During the cold war, the same waters became the scene of intense, clandestine cat-and-mouse games between Soviet and Nato submarines. For decades, the gap formed the critical barrier that Soviet attack submarines had to cross to threaten Atlantic shipping lanes.
New developments in AI and autonomous navigation have the potential to revolutionise sub hunting.
One of the frontrunners for the contracts — 26 companies have bid, according to the MoD — is Helsing, a German UK start-up that makes the SG-1 Fathom underwater glider. The Fathom carries an onboard AI system called Lura, designed to classify acoustic signatures of ships and submarines detected by its sensors.
In theory, hundreds of small, inexpensive gliders could form a dispersed detection mesh across the north Atlantic.
“If you’re trying to find a needle in a haystack, it stands to reason that it helps to have a lot more things searching for the needle,” said Amelia Gould, Helsing’s general manager for Maritime.
But technology alone is not enough, say experts, who have doubts that even the latest passive acoustic sensors can hear the latest generation of Russian submarines.
“It’s all massively difficult as the Russian submarines have been getting quieter since the 1980s,” said John Foreman, a Royal Navy warfare specialist and former UK defence attaché in Moscow.
Hunting submarines, he said, required both active and passive technologies, including bi-static sonar, where one ship transmits a sonar pulse and another receives the echo, a system employed on the Royal Navy’s new Type 26 anti-submarine frigates, which will form the backbone of Atlantic Bastion.
Eight Type 26s will be built for the UK, with Norway constructing five more for its own navy.
In naval parlance, a bastion is a protected safe zone — Russia’s own bastion, for example, is the Barents and White Seas, where its ballistic missile submarines operate under heavy protection.
Even if Atlantic Bastion succeeds in restricting Russian attack submarines, it will do little to deter their nuclear-armed ballistic missile fleet.
“Russia’s strategic submarines no longer need to leave the Russian bastion,” said one Norwegian former submariner.
“Their ICBMs can already reach the US and Europe from within it. They may therefore remain hidden, playing hide and seek, well within the Barents Sea.”