LONDON — Britain’s undersea infrastructure is highly vulnerable to Russian sabotage.

That’s the stark warning from defense and energy experts ahead of the country’s major strategic defense review, expected next week.

They warn that critical gas pipelines, power lines and data cables are the “soft belly of British security” — leaving the country exposed to potentially “catastrophic” sabotage at the hands of Russia or other enemies.

The British government — which is hiking defense spending — said last month that it will address the threat to pipelines and other undersea infrastructure as part of its review, expected Monday.

It comes amid rising tensions with Putin’s Russia, and at a time when Europe is already on alert over a spate of potential sabotage incidents affecting subsea cables and pipelines.

But U.K. experts, including former senior government officials, believe the dangers are being underestimated.

In an interview with POLITICO, Grant Shapps, who served as both energy and defense secretary in the last U.K. government from 2022 to 2024, said “complacency” about the problem was “genuinely worrying.”

“Our undersea infrastructure is a sort of soft belly of British security, and not enough is being done,” Shapps said. 

“It’s not a question of if there’ll be a problem at some point, it’s when there’s a problem. This should be a much higher concern for the government. And I don’t just mean that it’s placed on a risk register somewhere. … [We need] a national endeavor, a national plan to protect our undersea infrastructure.”

Nord Stream style

Undersea infrastructure is “one area” the defense review will examine, ministers have said. The U.K. and its allies have already increased naval patrols and increased monitoring to combat threats to infrastructure.

But while much of the political focus has centered on data cables, security and energy experts warned that the greatest risks could come from an attack on a gas pipeline — like the mysterious 2022 attack on the Nord Stream pipeline in the Baltic Sea.

The U.K. is more dependent than most G7 countries on gas to warm homes and provide electricity. More than half of demand is met by imports, chiefly from Norway, and most Norwegian imports come via a single pipeline — the 715-mile long Langeled, which was built in the 2000s and remains one of the country’s vital energy arteries.

“Langeled is our single biggest point of weakness,” said Adam Bell, a former Whitehall head of energy strategy, now director of policy at the Stonehaven consultancy. “It doesn’t mean we would all keel over and die if it were blown up — but it means everything gets a lot more expensive quickly. You move toward a risk of rationing [the gas supply].”

While the odds of an attack are “pretty low,” the impact would be “catastrophic,” said Jack Richardson, who was an adviser to former Energy Secretary Claire Coutinho under the last Conservative government and is now an associate fellow at the Council for Geostrategy and head of policy at Octopus Energy.

“There is no other way of putting it. If Langeled gets knocked out we’re in massive trouble as a country,” he said.

Sidharth Kaushal, a senior research fellow in sea power at the Royal United Services Institute think tank, said Putin’s Russia had “invested fairly considerable resources into capabilities that could be used to sabotage critical national infrastructure.”

An open attack on U.K. infrastructure would be an act of war, meaning any such attempt by Russia would likely be covert. But the government should be alive to the risks that might unfold “on day one” of a potential conflict or “in the transition from crisis to conflict,” he said, should Russia seek to cripple the U.K.’s energy supply before hostilities even began.

“Given that’s a narrow window of opportunity for them, they’d probably go after areas where they think there are minimal redundancies,” Kaushal added. “Langeled is an obvious example. … I definitely see that as an important part of their approach to the opening days of a conflict or the build-up from a crisis to a conflict.”

Network emergency

The U.K.’s ability to weather any attack would largely depend on wider questions of supply and demand, including whether the country was experiencing a cold snap, how much gas was held in storage, and whether more liquefied natural gas (LNG) — super-cooled gas that can be traded around the world via tankers — could be procured on the international market.

The U.K.’s biggest LNG supplier is the United States.

“The big risk is that you lose Langeled and the U.S. stops sending LNG cargoes, which is painfully plausible,” said Bell. “We could probably endure one but not both without rationing.”

The reliability of U.S. support in that scenario is “impossible to know” and “depends on what goes through Trump’s head at 3 a.m.,” Shapps said.

If sufficient quantities of gas could not be found to replace lost supply — for example, in the event of an attack on multiple pipelines — a Network Gas Supply Emergency could be declared. These procedures are enshrined in law but have never been triggered since the U.K. gas network was built in the 1960s.

Initially, gas power stations could be shut down, leading to power cuts. These could be turned back on again quickly when the gas supply returned to normal, but in more extreme scenarios, factories and businesses — and, as a last resort, some households — could be cut off from the gas network entirely.

Energy industry experts, granted anonymity to discuss crisis planning, said in the event of such a drastic step, individual engineers would be required to reconnect each home to the gas network safely. It could take months before the network was back to normal, they said. 

Ireland, which is dependent on gas imports from Britain, would also be badly affected.

The U.K.’s latest National Risk Register, published earlier this year, contains a “reasonable worst-case scenario” of a terror attack on gas infrastructure that leads to “rolling power cuts lasting up to three hours,” and predicts that “restoration of the affected gas infrastructure could take approximately three months.”

Asked what he considered the most dangerous sabotage scenarios for the U.K., Shapps said he was “cautious about saying what my ‘lay awake at night’ greatest fears were, because it would lead somebody to the answer.”

“It’s unlikely that all our gas pipelines will be cut at the same time. But [let’s] argue in this case they were and we had zero gas — you’d look to bring in more LNG, you try to compensate in a whole variety of different ways. I think the most serious attack [would be] a really combined attack of energy and on data cables — then you’re in a different level of difficult.”

Get off gas

The U.K. still meets around half its gas demand through domestic supplies from the North Sea, but the quantities left in the ground are diminishing.

Richardson and Bell both argue that in the long-term, the way for the U.K. to guarantee its gas security is to reduce dependence on these fossil fuels.

The Labour government plans to cut gas from the power system almost entirely by 2030, but Richardson argued ministers should also “be doing way more on the consumption of gas, particularly for heat.”

“The simple answer is, you’ve got to diversify as much as possible, including away from oil and gas,” Shapps agreed, but added that in the short term ministers should drop plans to ban new gas exploration licenses in the North Sea and eke out as much as possible from domestic supplies. 

“It is completely idiotic and based on ideology to stop digging our own oil and gas,” he said.

A government spokesperson said: “Our priority will always be maintaining our national security, and protecting subsea and offshore infrastructure. 

“Alongside our NATO and Joint Expeditionary Force allies, we are strengthening our response to ensure ships and aircraft cannot operate in secrecy near the U.K. or NATO territory, harnessing new technologies like AI and coordinating patrols with our allies.”

Gassco, the Norwegian firm that operates the Langeled pipeline, did not respond to a request for comment.