Nine of the roughly 64 subsea cables reaching UK shores land at a single beach in Cornwall, and just two of them carry three-quarters of Great Britain's transatlantic data capacity. Parliament's security committee calls that clustering a target. The cable industry counters that four faults in five are still caused by fishing gear.
Around 64 cables land in the UK, of which 45 are international systems and roughly 50 are thought to be active.1 They do not spread evenly around the coast. Parliament's Joint Committee on the National Security Strategy (JCNSS) found that a vessel sailing from Land's End towards Aberystwyth would cross around 20 cables, and a ship working down the Suffolk coastline would cross eight major cables in a few hours.1
Two stations carry a disproportionate share. Lowestoft in Suffolk hosts five cables; Bude in Cornwall hosts nine — between them, roughly a fifth of every cable landing in the country.1 The committee's judgement was direct: landing stations may be the most vulnerable part of the whole system, physical security across sites varies, and some could be rendered inoperable by sabotage.1
Redundancy arguments usually start from the number of cables. The committee heard that this is the wrong denominator. Matthew Bowden of Red Penguin Marine told MPs it is the capacity of the cables cut, and the ability to reroute, that matters — not simply how many were severed.1
On capacity, the concentration is far sharper than the cable count suggests. Evidence submitted by Jeremy Steventon-Barnes, a former chief technology officer at EXA Infrastructure, and cross-checked by the committee against other sources, put two transatlantic cables at around 75% of Great Britain's transatlantic capacity and seven at around 93%.1 Twelve cables connect Great Britain to North America in total, and the two carrying the largest share both come ashore at Bude.2
The inquiry was prompted by a run of incidents in European waters. In November 2024 the Russian research vessel Yantar — described by the Defence Secretary as a spy ship used to map UK underwater infrastructure — was detected loitering over critical subsea infrastructure in the Irish Sea, and was shadowed by two warships, maritime patrol aircraft and RFA Proteus before leaving UK waters.1 In the Baltic, the Chinese-flagged Yi Peng 3 dragged its anchor for some 300km across two cables, and Finland boarded and impounded the tanker Eagle S, later charging three crew members.13
On capability, the committee's evidence is specific. Russia's deep-sea directorate, the GUGI, operates titanium-hulled vessels able to reach cables at extreme depth, though these need motherships for long voyages and exist in small numbers.1 Elisabeth Braw of the Atlantic Council told the committee Russia is willing and able to recruit freelancers for cruder work such as anchor-dragging.1 Set against that, Commodore (Rtd) John Aitken said destroying large numbers of cables at once would be extremely difficult, and a 2019 fire that put a key Russian deep-sea submersible into years of repair illustrates the readiness constraint.1
The important counterweight comes from the industry itself. The European Subsea Cables Association told the committee that sabotage is rare and the overwhelming majority of faults are not malicious: 70–80% of cable faults arise from fishing activity or vessels dragging anchors, and 20–30% from other non-malicious causes such as abrasion, equipment failure, seafloor currents or storms.1 On those figures, deliberate attack is a residual category, not the main event.
Not every chokepoint carries continental traffic. Some are a single lifeline to a small population, and those fail more often. SHEFA-2 links the Faroe Islands, Shetland, Orkney and the Scottish mainland, and it has been cut and repaired repeatedly — twice in 2013, twice within five days in October 2022, and twice more in 2025.6
The 2022 pair was the most disruptive: police declared a major incident and shops could not take card payments for a day.5 In July 2025 a fishing vessel struck the Orkney–Banff leg and service took 12 days to restore; ten weeks later Storm Amy broke the same stretch of seabed, and full restoration took almost four weeks.6 Faroese Telecom attributes the breaks to fishing gear or shallow-water seabed conditions rather than sabotage.7 The JCNSS cited exactly this pattern as evidence that outlying islands invite localised sabotage that would carry outsized political weight in a crisis.1
Alasdair Wilkie of the Atlantic Cable Maintenance & Repair Agreement told the committee that repair ships sail within 24 hours of notification and travel at around 12 knots. A fault in the Irish Sea might mean up to two days' transit and five days' repair; a mid-Atlantic fault seven days' transit and ten days' repair. Bad weather can stretch either to a month.1
Capacity is the constraint. The two main repair consortiums have three vessels each and could field two apiece in the North Atlantic, and each ship works one break at a time — so simultaneous faults queue.1 The UK has no sovereign repair capability: the UK-flagged CS Sovereign was built in 1991 and is expected to retire around 2030, and Global Marine, formerly a UK company, was acquired by a Singapore-headquartered fund in 2025.1 The committee recommended the government acquire a sovereign repair ship by 2030; in its December 2025 response the government said it was exploring a range of options rather than committing.4
No regulator publishes traffic by landing station, so Exhibit 01 counts cables — a station with many old, low-capacity cables is not the same risk as one with two new high-capacity ones, which is precisely why Exhibit 02 exists. The committee deliberately withheld its estimates of which cables would have to be cut to trigger a rerouting failure, and did not name the two cables carrying 75% of transatlantic capacity; it also chose not to publish parts of its vulnerability assessment. Capacity figures are theoretical design capacity, and the committee notes live "lit" capacity is lower by an unstated margin. The 31-cable residual in Exhibit 01 is arithmetic, not an itemised list. Cause-of-break findings for SHEFA-2 rest on the operator's own assessment rather than independent forensics. And on the central question — how much damage the network absorbs before data stops rerouting — the committee found no one, in government or industry, who could give a firm answer.1
The facts are largely agreed. What they add up to is not — and the disagreement runs between a select committee and the minister who gave evidence to it, which is unusually explicit for a technical brief.
Sir Chris Bryant, then telecoms minister, told the committee it was "overegging this pudding": the UK has 64 cables, more than islands its size normally have, and severing even all transatlantic links would reroute within hours.1 BT's Alex Towers said a broad degradation was hard to imagine given a century of protecting the infrastructure, and the industry body warned that claims of rising threats are not borne out in the fault data.1
The committee rejected that reading, finding the government's concept focuses too much on "having lots of cables" and too little on whether the network can absorb shocks.1 Sir David Omand, a former GCHQ director, warned the UK should expect Russian attention after a Ukraine ceasefire. The committee concluded operators have little commercial incentive to prepare for a crisis that may never come, and that government has a duty to.1 The point is not new: Policy Exchange urged a review of physical security at UK landing sites three years earlier.8
The committee compiled recent enforcement cases to test what an assertive response achieves. None involved UK cables being cut; the Yantar case is the only one in UK waters.
| Date | Vessel | Location | Action taken | Outcome |
|---|---|---|---|---|
| Nov 2024 | Yi Peng 3 | Baltic Sea | Boarding observed under Chinese restrictions; no criminal investigation permitted on board | Left the area; no arrests. Swedish investigators could not determine whether damage was deliberate |
| Nov 2024 | Yantar | Irish Sea | Two warships, patrol aircraft and RFA Proteus deployed; a submarine surfaced nearby | Ceased loitering and left UK waters |
| Dec 2024 | Eagle S | Baltic Sea | Boarded by Finnish authorities, escorted to port and impounded; crew detained | Released Mar 2025; three crew later charged with aggravated sabotage |
| May 2025 | Jaguar | Baltic Sea | Estonia sent a patrol ship, helicopter and aircraft to intercept; vessel refused instructions | Russia scrambled a fighter jet, briefly entering Estonian airspace; NATO jets responded. Boarding called off |
Compiled from the JCNSS report's enforcement table.1