In this guest article, Tom Rooney considers the impact of uncrewed systems and artificial intelligence on the undersea battle.

In the quiet expanse of the North Atlantic, an old strategic contest is being redrawn. Once the domain of Cold War cat-and-mouse games, the world of submarines has re-emerged as a fulcrum of 21st-century power politics. This time, however, the rules are changing.

Anti-Submarine Warfare (ASW), long the preserve of skilled sonar operators and warship commanders, is being transformed by a convergence of advanced technologies. Artificial intelligence, autonomous platforms, and real-time data integration are revolutionising how navies detect, track, and neutralise underwater threats. In a world where national security increasingly depends on mastering the invisible, the silent war beneath the waves has never been more important. And today, the silent partners in that war are becoming significantly more intelligent.

Resurgence below the surface

From the frigid depths of the Arctic to the contested waters of the South China Sea, the submarine is back at the forefront of naval strategy. NATO commanders have noted a surge in undersea activity reminiscent of the Cold War, driven by the strategic ambitions of Russia and China .

In May this year, the Royal Navy’s HMS Tyne tracked the Russian submarine Krasnodar, a Kilo-class diesel-electric boat, as it passed through the English Channel, highlighting continued vigilance amid rising tensions. Just a month earlier, U.S. Indo-Pacific Command leadership called for increased undersea surveillance in response to China’s expanding and modernising submarine fleet. At the same time, several emerging naval powers are investing in new-generation diesel-electric submarines designed for stealth and endurance, often equipped with air-independent propulsion to evade even advanced detection systems.

Submarines are now quieter, harder to detect, and operated by a growing number of actors with strategic intent, and the underwater battlespace is no longer passive. It’s dynamic, contested, and increasingly crucial.

Artificial intelligence enters the fray

Traditionally, ASW has been a resource-intensive operation, requiring specialised equipment and highly trained personnel to interpret sonar signals, deploy sonar buoys, and command swift action. But in recent years, AI has begun to reshape this model.

Emerging maritime technologies now harness real-time analytics and machine learning to equip unmanned vessels with the capability to identify, evaluate, and respond to sub-surface threats.

The oceans are saturated with acoustic and electromagnetic data, but human analysis alone can miss the subtleties. Advanced systems can learn from patterns in the noise, distinguishing between marine life, civilian traffic, and credible threats. The key to this advancement is ‘sensor fusion’, the integration of sonar, radar, and satellite feeds into a single intelligent platform. For commanders, this means faster decision-making. In the unforgiving world of ASW, where response times are often measured in seconds, AI doesn’t simply support a mission, but accelerates it.

The Mayflower Autonomous Ship, a groundbreaking research vessel that has crossed the Atlantic Ocean using AI and without any human intervention. This technology has the potential to form the basis for the ‘Type 93 sloop’ envisioned by the Royal Navy’s project CABOT using autonomous ASW platforms that can be deployed with sensors to hunt submarines in the GIUK Gap.Autonomy in action

At the core of this new doctrine are autonomous surface vessels (ASVs) and uncrewed underwater vehicles (UUVs) equipped with AI-driven systems. These platforms, often small and stealthy, serve as tireless sentinels, continuously scanning their environment, predicting hostile movement, and sharing intelligence with manned forces. Such systems can be retrofitted onto existing vessels or integrated into new builds, transforming them into intelligent, decision-capable assets.

This level of autonomy enables persistent presence without persistent risk. These vessels can loiter for days, weeks or even months, actively listening and analysing, keeping human lives out of harm’s way.
Looking ahead, task forces may deploy networks of AI-powered vessels to form invisible perimeters, detecting adversaries long before they threaten high-value assets such as carrier strike groups or vulnerable undersea cables.

The strategic implications are profound. ASW, once reactive and person-power heavy, is becoming pre-emptive, distributed, and dramatically more cost-efficient.

Doctrine in transition

The UK’s most recent Strategic Defence Review outlines a sharpened focus on undersea security and resilience, highlighting the growing threat posed by hostile submarine activity and sabotage of subsea infrastructure. The review commits to investing in autonomous maritime capabilities, enhancing the Royal Navy’s ability to operate in contested environments with reduced risk to personnel. It also reinforces the importance of multi-domain integration, ensuring that undersea, surface, air, space, and cyber capabilities can work together to deliver maritime superiority.

Yet, with new capabilities come new challenges. Integrating AI into command structures requires updated training, revised doctrine, and ethical considerations around machine-led decisions in high-stakes environments.

Despite the UK’s rich engineering talent and a strong foundation in uncrewed vessel innovation, industry insiders warn that regulatory bottlenecks are hindering progress. Developers of autonomous maritime platforms have voiced concerns over outdated certification pathways, urging faster, clearer regulatory reform to ensure the UK does not fall behind more agile global competitors. As a sector, we are confident that the UK could lead NATO in water-based autonomy, but only if its regulatory framework keeps pace with its technological ambition.

Securing the subsea frontier

Beneath the world’s oceans lies a vast and increasingly vulnerable network of infrastructure. From data cables enabling global communication to pipelines transporting critical energy supplies, the subsea environment is both a battleground and lifeline. And as geopolitical tensions mount, these systems become attractive targets for state and non-state actors alike. The ability to monitor and protect them is fast becoming a national security imperative.

Advanced ASW capabilities offer not only a tactical edge but a strategic shield. Autonomous systems, operating around the clock, can detect anomalies near sensitive infrastructure, track suspicious activity, and provide real-time alerts to human operators. We’re not just talking about defending fleets – we’re talking about defending the arteries of the modern world.

The Oceanus12 has been developed by Zero USV in collaboration with MSubs and Marine AI as a fully autonomous, low-carbon USV designed for over-the-horizon missions.The intelligence edge

While adversaries invest in stealthier submarines, the West’s answer is not just bigger fleets, but smarter ones. Intelligence, surveillance, and reconnaissance has long been the lynchpin of maritime dominance, but the difference is that AI is central to this mission.

By learning from every sonar return, every data point, and every engagement, these intelligent platforms evolve. Over time, their insights grow sharper, their predictions more accurate. This dynamic learning loop ensures that the longer these systems operate, the more capable they become. Such adaptability is essential in an environment that never stops developing. The oceans are fluid, threats morph and tactics evolve. A static defence is no defence at all.

A quiet revolution with loud consequences

The undersea realm remains one of the most complex operational environments on Earth. But with AI and autonomous technologies maturing rapidly, the balance is shifting. Where once submarine warfare was a game of patience and guesswork, it is becoming a battle of algorithms and machine logic. In this new underwater arms race, silence may still be golden, but intelligence is priceless.

As navies adapt to a world where the first warning of attack may be a data point rather than a sonar ping, the tools to stay ahead are evolving. The future of undersea warfare will not be won by the loudest or even the strongest force. It will be won by those who can see the unseen, think faster than the threat, and act before the danger breaks the surface. The silent war has never been more sophisticated, or more vital.

Tom Rooney is the General Manager of Marine AI, and is a trained engineer, having served in the Royal navy for 25 years and known for deep expertise in radar, sonar, external communications and marine operations. Marine AI is the software house of MSubs, set up to commercialise its autonomous and AI software for the defence, commercial and recreational markets.