UK needs better defences to protect undersea internet cables from Russian sabotage

UK is dependent on subsea internet cables

The UK is a global hub for internet traffic, and almost entirely reliant on subsea cables to exchange data with other countries.

The UK has about 62 subsea cables, about 50 of which are thought to be active, to connect it with the rest of the world and to provide resilience if some are deliberately or accidentally damaged. Additional cables run through the Channel Tunnel.

MPs and peers warn in their report that a simultaneous attack on multiple cables, particularly during times of heightened tension or conflict, could cause significant disruption.

There is growing concern about malicious reconnaissance and sabotage of the UK’s underwater infrastructure, they say in a report published today.

Parliament concerned over Russian threats

Experts told the committee that Russia operates titanium-hulled vessels that can target cables at extreme depths and is willing to recruit freelance shipping operators to damage undersea cables by dragging their anchors.

In January, Russian spy ship Yantar was challenged in British waters after being observed “gathering intelligence and mapping the UK’s critical underwater infrastructure”.

MPs and peers say the UK’s outlying islands, military cables and cables used by the financial sector are vulnerable. While sabotaging these links may not cause national disruption, it would be “costly, provocative and hard to prevent”.

Their report says that onshore landing stations, such as Lowestoft, which houses five cables, and Bude, which houses nine cables, could also be at risk, and that some sites could be “rendered inoperable” by sabotage.

Risk of ‘catastrophic disruption’

The committee said coordinated attacks could cause catastrophic disruption, including failures in payment systems and supply chains, degraded communications, overstretched emergency responses, and unexpected cascading issues as online authentication applications are disrupted.

When a fishing vessel accidentally severed cables to the Shetland Islands in 2020, residents reported widespread card payment failures, and disruption to mobile phones and landlines.

Damage to a cable connecting Orkney and Banf in 2025 disrupted business internet connections and led to the closure of a hospital switchboard.

The financial sector relies on subsea cables for high-frequency trading, with over $1.5tn in cross-border trade travelling through undersea cables each day.

The loss of key low-latency connections combined with damage to backup routes could cause “significant disruption”, the committee said.

UK needs better preparation

The parliamentarians call for more robust resilience plans, particularly in the financial sector, and updated contingency planning to account for damage to onshore landing stations.

Their report recommends that the government acquires a cable repair ship by 2030, to address the lack of a sovereign repair capacity.

It also calls on the Royal Navy to establish a cadre of reservists and serving personnel to learn cable repair skills, to ensure cables could be repaired in the event of a conflict.

Other recommendations include scaling up cable monitoring schemes, rapid data sharing with law enforcement, legal sanctions, and a greater focus on “direct physical interdiction and prosecution” of suspicious vessels and crew.

Matt Western, chair of the Joint Committee on the National Security Strategy, said the undersea cables form the backbone of the internet, and carry financial transactions worth billions of pounds. “The scale of the UK’s strategic reliance needs to be taken more seriously,” he added.

“We must prepare for the possibility that our cables can be threatened in the event of a security crisis,” said Western. “Putin has shown every sign of wanting to test the soft underbelly of the Nato alliance. Our cables are sufficiently vulnerable to make them a target.

“We need stronger physical protections, better options to impose genuine costs for malicious activity and more comprehensive recovery plans,” he added. “It is conceivable that the UK’s national resilience will be tested in the coming years. We need to be ready.”