The Joint Committee on the National Security Strategy (JCNSS) has recommended that His Majesty’s (HM) Government acquire a sovereign capability for cable repair by 2030. With the United Kingdom (UK) already committed to resource sharing with the North Atlantic Treaty Organisation (NATO) and the Joint Expeditionary Force (JEF), how important is a sovereign capability for the security of British Critical Underwater Infrastructure (CUI), and what options does HM Government have?
The necessity of cable repair capability
In the early 20th century, British telecommunications companies championed the undersea cable industry, with giants such as Cable and Wireless operating 14 cable ships out of British ports by 1929. These ships, while private, could be requisitioned by the state in times of need – as would happen ten years later in 1939. The UK’s success in maintaining its CUI during both world wars owed much to the rapid response made possible by these privately owned, British-based assets.
Today, the UK relies more heavily on CUI than ever before. Upwards of 97% of communications data transits the undersea cables that also carry the data underpinning the economy. Indeed, £1.4 trillion in daily British transactions – 23% of the world’s total – relies on subsea cables.
In peace time, damage is rare and manageable. As Al Carns, then Minister for the Armed Forces, told the JCNSS in May 2025, the UK averages five cable breaks a year, 80% accidentally caused by routine shipping (primarily anchor drag). These breaks are generally repaired within eight days – a rate three times faster than the global average. However, a wartime precedent for the strategic importance of cable repair means that Britain cannot take peacetime performance for granted.
Severing communications cables has historically been an efficient way to disarm and disorient an adversary early in a conflict before other forms of engagement occur. As an island nation with security commitments across the Irish Sea, the High North, and to European allies, the UK’s posture needs to be agile and proactive; ready to respond quickly to several simultaneous incidents at once, and across a substantial geographic range.
What is available today?
Multilateral cooperation towards defence of CUI has increased significantly over the past ten years, providing different routes for Britain to contribute both to its own and to allied CUI protection. The UK currently has access to just three cable repair ships through the Atlantic Cable Maintenance and Repair Agreement (ACMA). Four cable ships owned by Keppel Corporation, a Singaporean company, are registered to Britain, although these ships have competing national contracts.
More broadly, the UK is involved in CUI defence initiatives through NATO, such as BALTIC SENTRY and hosting NATO’s Maritime Centre for the Security of Critical Undersea Infrastructure within the alliance’s Maritime Command; through the JEF via Operation NORDIC WARDEN; and with AUKUS investment in Uncrewed Undersea Vehicles (UUVs) to protect undersea cables.
Britain does, of course, also benefit from support from its allies. France has access to around nine French-flagged repair vessels, and Norway and Italy have three each. However, in the event of war and a period of sustained attack on communications, allies will have their own priorities to contend with, and it is uncertain whether these capabilities would be enough.
It is unlikely that the UK will be operating alone in a period of sustained attack. However, considering the burden of being an island nation, relying on 64 communication cables and ten subsea electricity interconnectors – alongside the reliance on transatlantic cables that is not felt so acutely by its European allies – a sovereign capability would be beneficial for national security.
The sovereign fleet solution?
British industry leaders have raised concerns about reliance on foreign-flagged repair ships, as well as the security implications of cable repair passing through foreign-owned companies. Many ships are foreign-flagged and foreign-crewed, which leads to complications in wartime repairs. Current insurance for commercial vessels does not cover war risk, and crews are not necessarily prepared to sail into contested waters once standard cover lapses.
Furthermore, governmental war risk insurance, as envisioned in the War Risks Act of 1952, is untested in the modern environment where ‘grey zone’ threats are more likely than a declared, conventional war. This is the sort of political reality technically required for the roll-out of governmental war risk insurance schemes.
In both peacetime and wartime, the UK has the responsibility to help lead a NATO and JEF cable repair effort, potentially built around the Royal Fleet Auxiliary (RFA), with sovereign capabilities – a unique position given Britain’s geography spanning the High North, the continental shelf shared with Ireland, and its role supporting Euro-Atlantic allies.
The JCNSS’ 2030 target is not arbitrary. ACMA’s UK-based CS Sovereign was built in 1991 at a cost of £32 million, and cable repair ships typically have a service life of 35-40 years, meaning its retirement is on the horizon. Without taking action, Britain risks losing even its existing, modest access to domestic repair capacity just as the geopolitical threat picture worsens.
A sovereign fleet solves many of these problems, but comes at a huge price. CS Sovereign cost £32 million while RFA Proteus cost £70 million to purchase in 2023. A dedicated repair vessel would cost a similar amount to the latter. However, a full sovereign fleet is not necessarily required, nor affordable or politically palatable. A middle path, closer to the United States’ (US) retainer model and Cable Security Fleet – whereby Washington has paid privately owned, US-flagged vessels an annual retainer of US$5 million (£3.8 million) for guaranteed availability for laying, maintaining, and repairing critical cables – is more realistic.
This option would comprise one or two UK-owned, UK-flagged vessels using the benchmark of £70-£100 million set by RFA Proteus as a financial guide. It would be backstopped by retainer agreements with multinational operators covering the remainder of Britain’s current access to roughly seven vessels (through the ACMA and Keppel-registered vessels), alongside government-backed wartime insurance. In peacetime, these could be leased to industry when necessary.
The personnel factor
A further, and often underappreciated, area of undersea cable repairs, both today and throughout history, is the skill and training necessary to fix the cables and operate the vessels required. During both world wars, cable ships were sitting ducks while the specialist crews worked tirelessly to repair the UK’s telecommunication cables. Notably, the CS Alert was sunk in 1945 while carrying out this exact mission.
An additional bottleneck arises around the importance of a trained British crew. John Wrottesley, Executive Director of the European Subsea Cables Association, told the JCNSS directly that ‘skills and workforce is probably one of the most pressing challenges’ facing the sector, not just training naval reservists. Alasdair Wilkie, Chairman of the ACMA, also told the Committee that a repair ship takes around three years to build, while the staff needed to crew and operate a vessel takes closer to ten years to train.
Wrottesley similarly expressed a need for better support from HM Government on cable repairs in a ‘conflict-type situation’. A trained, sovereign crew solves a critical challenge in the UK’s repair capabilities by providing British personnel for commercial vessels attending to cable damage in wartime that would not be covered by standard insurance. However, given the ten-year training horizon, a workforce programme started today would only reach maturity around 2036 – six years after the JCNSS’ own capability deadline.
Conclusion
Over the next 10-15 years, the UK’s dependence on undersea cables is expected to increase. As the British economy digitises, data traffic will increase in line with increased investments in Artificial Intelligence (AI), 5G and 6G, and the Internet of Things (IoT). These important technologies require protected and capable undersea cables.
In peacetime, a middle-path, hybrid, sovereign capability would reinforce the UK’s position as a leading maritime security provider – an island economy dependent on cables, with responsibilities towards the Republic of Ireland, the High North, and NATO and JEF allies. In wartime, it would offer a capability better matched to the task of CUI repair in a contested and targeted contingency, as was guaranteed during both world wars. HM Government should therefore look towards internal training issues while acquiring the base of a sovereign repair fleet, new retainer contracts between itself and private repair vessels, and the means to protect these crucial capabilities.
Liberty Hunter is the Sir Julian Corbett Adjunct Fellow in Maritime Security at the Council on Geostrategy. She works as a Project Manager and Researcher at the Ax:son Johnson Institute for Statecraft and Diplomacy, and is also a Research Associate at the Hertford College Diplomacy Centre.
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What do you think about this Memorandum? Why not leave a comment below?
Interesting. The political intent to make good our lack of repair capability is as evident as the lack of investment in our Armed Forces.
One point that may deserve consideration is to stop fishing vessels from using drag nets around our coasts. Our national problem being we have virtually no current capabilities to 'police' this and our other critical sub-surface cables and pipelines.
Can we make the case for on-shoring the data centres that these vulnerable cables lead to? Spending on reinforcing a strategic weakness may not be the best solution.