A newly published report from the UK Parliament’s Joint Committee on the National Security Strategy (NSS) has issued a stark warning about the country’s heavy reliance on subsea cables, calling for urgent action to strengthen their security and resilience.
With more than 99% of the UK’s international data traffic transmitted through these fibre-optic cables laid on the ocean floor, the nation’s digital infrastructure is at growing risk from a complex mix of geopolitical tensions, cyber-physical threats, and natural hazards.
The NSS Committee is now calling for sweeping reforms to how the UK monitors, secures, and manages these vital arteries of the internet.
“Our modern economy, security, and society depend on these cables,” the report states. “Their resilience is a matter of national security.”
Subsea cables have long been the invisible backbone of global connectivity, yet £65 billion of UK economic activity relies on the subsea cable industry. But what was once considered a niche concern among telecom engineers is now a frontline issue for national defence and foreign policy.
The committee’s 2024–26 parliamentary session report shines a spotlight on just how vulnerable this infrastructure has become.
Among the most alarming revelations is the emergence of deliberate sabotage as a credible threat. The report details how state and non-state actors (equipped with remotely operated vehicles (ROVs), autonomous underwater drones, and seabed surveillance capabilities) could exploit weak points in the subsea cable network as part of hybrid or asymmetric warfare.
Russia and China named as leading threat actors
The NSS report explicitly names Russia as the UK’s most immediate and capable threat actor in the subsea domain. Russia’s strategic posture, naval capabilities, and past use of hybrid tactics, including cyber-attacks and grey-zone military actions, combine to present a “severe national disruption” risk to the UK.
China, while currently more focused on the Indo-Pacific, is also called out for its growing maritime capabilities. The report cautions that in the event of a UK deployment in support of Indo-Pacific allies, retaliation could take the form of targeted disruption to subsea cables or associated infrastructure.
The report doesn’t rule out non-state actors either. The 2024 Houthi attacks in the Red Sea, which indirectly impacted subsea cables, and a September 2025 incident affecting Microsoft’s Azure services, have both highlighted how vulnerable undersea infrastructure is, even when state-level involvement is unclear.
“As autonomous underwater vehicles become more commercially available, new concerns may arise around terrorist or extreme direct-action organisations seeking to disrupt parts of the economy,” the report warns.
Geopolitical sabotage or maritime coincidence?
A 2025 report by the Research Institute for Democracy, Society and Emerging Technology suggests that damage near flashpoints like the Baltic Sea may be part of a deliberate campaign by Russia and China to probe vulnerabilities or send geopolitical signals.
The report indicated specific cases, including the “New Polar Bear” incident in October 2023, which saw pipeline and communication cables between Estonia and Finland damaged. The incident involved a Hong Kong-flagged container ship, whose captain was later detained in Hong Kong. The ship’s anchor was reportedly dragged across the seabed, damaging cables.
Additionally, the Yi Peng 3 case, saw a Chinese cargo ship conduct erratic movements across multiple cable routes in the Baltic Sea with its anchor down. Though damage occurred, a Swedish investigation ultimately found no conclusive evidence of intentional sabotage.
Foreign ownership
Ownership of subsea cables is another major concern. Much of the UK’s subsea infrastructure is privately owned, often by foreign consortia that include non-allied stakeholders. This poses obvious risks around access, oversight, and intelligence visibility.
Compounding the problem, the UK has limited domestic capacity to repair or respond to cable failures. The committee suggests the Royal Navy could expand its role as a force multiplier to defend and maintain the system. However, this raises further questions around escalation and deterrence.
“Deploying naval assets to protect cables could spark geopolitical tensions or trigger escalation,” the report warns.
Currently, cable security responsibilities are spread thinly across multiple government departments, regulators, private firms, and international bodies. The report calls for a centralised UK oversight body to streamline policy, intelligence-sharing, and operational command.
Atlantic Bastion: A NATO-Led response?
One of the more ambitious recommendations is the proposal for an “Atlantic Bastion”- a NATO-aligned, multilateral framework designed to monitor and defend subsea cables in the North Atlantic. The concept echoes Cold War-era collective security models but updated for a digital age where data routes have become as strategically significant as shipping lanes or airspace.
While the UK has a large number of subsea cable landings and routes, the report warns against equating quantity with resilience. Many cables land in just a few chokepoints, such as Cornwall, Suffolk, and Kent, creating systemic weaknesses.
Government response
The Committee questioned the minister for data protection and telecoms Sir Chris Bryant MP, who argued that a total transatlantic cable disruption was “unlikely” and dismissed it as a “moot point” in contingency planning.
“The Government’s resilience concept focuses too much on ‘having lots of cables’,” the report criticises. “It pays insufficient attention to the network’s actual capacity to absorb shocks.”
There also appears to be little consideration for onshore infrastructure vulnerabilities or how the cumulative effect of minor outages could degrade national connectivity.
For telecoms and cloud operators, this report could be a watershed moment. Investment in redundancy, encrypted routing, diversified landing stations, and real-time monitoring may no longer be optional.
Meanwhile, a broader public discussion is needed around infrastructure sovereignty, who builds and governs the systems on which modern life depends.
The NSS Committee’s report leaves no doubt: subsea cables are now a frontline issue in the UK’s national security strategy. As geopolitics moves beneath the waves, the industry, and its regulators, must be prepared to respond with speed, coordination, and seriousness.
As one committee member concluded, “We are no longer talking about “if’ but ‘when’, and how ready we are when it happens.”
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