Each day, trillions of dollars in financial transactions and more than 95% of global internet traffic travel through these conduits. Our reliance on them even extends to power, oil and gas which – together with communication networks – present an attack surface that must be protected.
While engineered for resilience, this critical infrastructure faces a growing array of threats as global security becomes more volatile – increasingly at risk of deliberate interference while still contending with accidental and environmental damage. Economic instability, complex and slow permitting environments that differ from country to country and an upcoming shortage of skills in the sector present further risks to this essential global network. Ensuring its protection is no longer just an industry concern, but a national imperative.
The conversation around critical national infrastructure must therefore expand to fully encompass the complexities of this global subsea network. A collaborative approach that unites government, industry and technology partners is essential to safeguarding these vital assets, ensuring data resilience and securing our digital future.
The complexities of subsea cables
The global network consists of approximately 1.3 million kilometres of submarine fibre optic cables, with 570 systems in service in 2025 and 81 more planned. The UK alone is connected to more than 60 international lines.
Managing cable breaks has been part of the cable operating model since the first transatlantic cable was laid in 1858. Multiple, geographically diverse cables make for a resilient global network, so when a cable breaks disruption isn’t usually felt. Cable operators have agreements in place to ensure that traffic is immediately rerouted, and special repair vessels are on call 24/7 to steam to the location and repair the cable.
However, damage to multiple cables simultaneously – particularly at choke points – can cause disruption potentially leading to lost business and reduced connectivity. And, for island communities with only one or two cables, a single cable fault can cause significant disruption or complete disconnection. Recent damage to cables in the Red Sea and Gulf of Guinea has highlighted this vulnerability – where sanctions and the volatile security situation in the Red Sea region prolonged the outage by slowing the repair process.
Of course, there is always a financial cost. Repairing a single fault in a fibre optic cable can cost up to £1million, with the cost of repairs for energy interconnectors often being significantly higher. The process involves dispatching a specialised ship to the fault location, retrieving the cable from the seabed and splicing in a new section.
The challenge is compounded by a complex governance landscape. In the UK, individual cables are the responsibility of their operators, but the collective network is considered part of the critical national infrastructure, making it a government concern. This shared responsibility can create a disconnect between the cable industry and government bodies, hindering a unified approach to protection. Furthermore, international by their nature, cables are often owned and operated by a consortium of companies from multiple countries connected through multiple jurisdictions. Resilience in one country can be hampered by a slow permitting process or delays to repairs in another country.
Threats below the surface
The most common threat to subsea cables is accidental damage from industrial fishing and merchant ships. Trawlers dragging nets along the seabed can snag and sever cables, while poorly secured anchors on merchant ships can deploy unknown during transit (especially during bad weather) and drag for hundreds of kilometres without the ship being aware. This is made more difficult to monitor as fishing vessels frequently turn off their Automatic Identification Systems (AIS) to protect their fishing grounds from rivals.
Beyond accidental damage, there is the growing risk of deliberate hostile action. In an era of geopolitical tension, the potential for state and non-state actors to target this infrastructure cannot be ignored. The ability to disrupt global data flows represents a powerful and asymmetric threat. Securing these assets therefore requires a new level of maritime domain awareness and a proactive security posture centred on early threat detection – moving away from traditional methods of subsea cable protection that focus on attribution to recoup the cost of repairs. Furthermore, civilian repair ships responding to cable faults should not be expected to enter a volatile security situation that could put them at risk.
This is where innovative technologies and strong partnerships become crucial. A robust solution involves bringing together government agencies, such as the Joint Maritime Security Centre and Royal Navy with telecom operators and technology providers. By combining resources and expertise, we can create a comprehensive system for monitoring and responding to threats to prevent cable damage and deter hostile action.
The goal is to build resilience, protect the immense value of the data being transmitted and achieve significant cost savings by preventing faults before they occur.
Forging a resilient future
The protection of our subsea cable network demands a united front. The technology to proactively monitor and protect these assets exists and is becoming more capable – one example being Distributed Acoustic Sensing (DAS), which transforms the fibre optic cable itself into a sophisticated sensor array to provide early warnings of threats.
Beyond technology, what is now required is the will to implement it through strategic collaboration. Industry operators can benefit from reduced operational costs and enhanced network reliability. Governments can strengthen national security, improve their ability to police their territorial waters and plan for a potentially deteriorating security situation. By investing in holistic technical solutions and fostering partnerships between the private and public sectors, we can start to move away from a reactive model of attribution and repair to a proactive strategy of prevention.
Ultimately, government and industry leaders must come together to invest further in the security of our shared digital infrastructure. By doing so, we not only protect our data and our economy, but also ensure the continued resilience and prosperity of our interconnected world.
Subsea Intelligence
We examine the challenges posed by the modern subsea domain and how nations can gain an advantage.