Why Energy Security Belongs at the Heart of Britain’s Defence Strategy

Ask someone to picture British defence, and they’ll likely picture steel. A frigate cutting across an ocean, a fighter jet on a Lincolnshire runway, or missiles firing over a peninsula. Almost nobody pictures a substation in Hayes, or a gas terminal on the Norfolk coast. This gap in the national imagination reflects a strategic liability Britain needs to address.

Weapons don’t fight wars alone. They need electricity to build them, fuel to move them, and an economy strong enough to finance them. A country can field one of Europe’s most advanced militaries and still be brittle if the grid, pipelines, or cables on the seabed aren’t sufficiently treated as a defence asset.

Russia’s invasion of Ukraine and the curtailment of gas to Europe did not have to empty our pipelines and hurt Britain. The price shock arrived faster than any shortage could, forcing the government to introduce eight support schemes now expected to cost £44 billion. Such spending is the cost of energy security operating in parallel, rather than in conjunction with national security, a cost the British taxpayer has had to bear.

Yet the latest official energy statistics show that the government has not learnt its lesson. Britain’s net import dependency remains at 43.3% as of 2025, with more than 90% of those imports being oil and gas, which still supply three quarters of our energy demand. While we did learn from the crisis to diversify our suppliers, and deepen our reserves, this has not happened fast enough, and diversity on a spreadsheet is a cold comfort if we continue to underplay the importance of terminals, shipping lanes, deep-sea cables, and the political consent behind them, to our national security.

The 2025 Strategic Defence Review describes attacks on critical infrastructure below the threshold of war as a daily occurrence, and gives the Royal Navy a frontline role in stopping them. Whitehall, in other words, is not oblivious. On that reading, a seabed cable or a substation transformer matters to the national endurance as much as a weapons platform does. Our adversaries have plainly reached the same conclusion. Why, then, are we so slow to act on our own analysis?

We don’t even need an enemy to prove this point. A fire at North Hyde substation closed Heathrow and cut power to more than 70,000 customers, and the government’s subsequent review traced it to a preventable technical failure, even with an Ofgem audit finding good practice sector-wide. So, the system was behaving roughly as intended and one junction still shut the country’s busiest airport. Now picture the same result achieved by design, in a targeted attack, rather than by accident; such as the one recently launched by Iran on a small power plant. Clearly, there is a deficiency in the way this country approaches energy security.

That being said, none of this is an argument for turning inward. Norwegian gas and European interconnectors make Britain stronger, so long as the routes stay protected. A North Sea drilling boom wouldn’t buy us price sovereignty either, given that 90% of UK crude is already exported because it doesn’t suit our refineries. You cannot engineer dependency out of a country this size. What you can do is map out where each dependency can be exploited and how they compound each other to reinforce our national resilience. 

Domestic generation still matters, renewables above all, because every megawatt-hour produced here is a unit no global incident can interrupt . Renewables contributed 52.1% of Britain’s electricity in 2025, with wind alone contributing 29.5%. However, generation is the easy part. Electricity must reach people, and it has to keep reaching them through a windless February. Our gas storage covers 13 days of average winter demand, and much of the nuclear fleet is heading for retirement. The transition can reduce exposure, but at the moment, it is opening bottlenecks faster than we are closing them. 

Underneath all of this sits a question of ownership that nobody much wants to answer. Energy is governed as a market and defence is a function of the state, while critical infrastructure sits awkwardly in between. That arrangement is comfortable in peacetime, but rather useful to an adversary in a crisis. Ask something simple, such as how long a naval base can operate if the grid goes down, and you get a regulator pointing at an operator pointing at a department.

The instinct to fix this with equipment is understandable, and Britain’s Atlantic Bastion programme will improve how we watch the North Atlantic. Spotting a severed cable is not the same as splicing it back together, though, and we hear remarkably little about who would do the repairing or how long we would be waiting.

Nobody can claim that the money isn’t there. NATO’s Hague pledge commits members to spend 5% of GDP on defence and security by 2035, with 3.5% for core military capability and up to 1.5% for exactly this kind of broader resilience. That 1.5% is an open invitation to count spare transformers and repair ships as defence spending, but it will be wasted if the Treasury misallocates the funds, or worse, defaults on its commitments.

The real measure of British defence is whether the country keeps working when the systems sustaining everyday life come under attack. Energy resilience is not adjunct to defence strategy; it is defence strategy, and treating it as anything less is a bet Britain cannot afford to lose.