An invoice is arriving for British defence. In Westminster, the argument is how to pay it. Spend more, says Lord Robertson, former Nato chief.

Spend faster. Britain is “underprepared”, “under-insured”, “not safe”. Keir Starmer promises to lift defence spending to 3 per cent of GDP, with Nato’s new targets pushing it higher still: 3.5 per cent on the military, 5 per cent on “security” by 2035.

The number rises. The plan does not exist. No one can yet say, in public and in detail, what this money is meant to buy.

Not which threats it answers. Not which vulnerabilities it reduces. Not which dependencies it ends. Just the percentage.

Robertson is not a neutral voice in this debate. As defence secretary, he authored the 1998 Strategic Defence Review that set Britain on its current course: an “expeditionary” military built to operate alongside the United States in global interventions, not primarily to defend the UK. As the historian David Edgerton observed at the time, Britain was committing itself to acting as Washington’s “principal partner”, with only a minority of spending directed toward national defence.

That force projection model – embodied in aircraft carriers – has endured. Robertson’s 2025 review largely leaves it intact. Today, he sits within the transatlantic defence industry he helped entrench, advising firms through the Cohen Group, calling for more money to be spent on the system that produced Britain’s dependence.

Cross the Atlantic and the logic becomes clearer. Donald Trump is pushing for a US military budget of $1.5 trillion – a vast expansion of the most heavily funded war machine in history. The markets understand what this means.

Since 2022, the share prices of Lockheed Martin, RTX, Northrop Grumman and General Dynamics have surged, pricing conflict in as a durable condition. War is a growth sector. And the US defence industry does not just benefit from public spending.

It helps shape it. The industry spends more than $100 million a year on lobbying, with tens of millions more flowing through campaign donations each election cycle. In Washington, the line between contractor and policymaker is often a door on a hinge.

The system does not simply respond to threats. It helps produce them – converting public fear into private profit. Britain is being drawn deeper into this circuit.

Money flows into politics. Politics amplifies threat. Threat justifies spending. Spending flows back as profit.

Or more plainly: Britain is being pushed to become a vassal purchaser in a US-led military market – paying more, for less control. The debate begins in the wrong place. Defence is framed as a share of GDP, as though a percentage were a strategy.

No serious state budgets healthcare or education this way. You decide what you need to do, then you resource it. Here, the sequence is reversed: a number set externally, internalised domestically, and justified afterwards.

The result is a ratchet without a plan. Then comes what that money actually buys. Britain’s procurement model routinely promises more than it can fund.

The National Audit Office (NAO) found the 2023 defence equipment plan is already £17 billion in the red. In plain terms: even before the next spending increase, Britain has committed itself to spending money it hasn’t budgeted for. More money into that system does not guarantee more security.

It guarantees a larger bill. But cost is only half the story. The deeper issue is dependency. Take the F-35.

The Ministry of Defence estimated the fighter jet fleet’s cost at £18 billion, but the full lifecycle cost runs towards £70 billion. And after all that, Britain does not control what it has bought. It relies on US-led architecture for maintenance, upgrades and software.

Even basic capabilities have been delayed. The return on investment, in the NAO’s words, has been “disappointing”. Trident is more politically guarded, but no less revealing.

The British governing and media class routinely presents the nuclear deterrent as the ultimate guarantee of independence. The system tells a different story. The missiles are American.

They are serviced in America. At key points, the system depends on the US Defence chiefs might call that sovereignty. But that is doing political work the hardware struggles to sustain.

There has not been a successful test launch in over a decade. Step back, and the pattern is unmistakable. Since 2022, arms imports to Europe have surged.

According to data from the Stockholm International Peace Research Institute, nearly two-thirds of those imports have come from the United States. At the same time, Europe has absorbed the shock of an energy crisis that transferred vast windfall profits to US firms. Transition Security Project research suggests that the EU and UK absorbed around $1.8tn in direct costs from the 2022-25 energy shock, while U.S. companies made $241bn in windfall profits in 2022 alone.

Energy and security alike: dependency deepened, and paid for. Even in war, the limits s