As the row over the military budget grows, Keir Starmer has spent much of the past few days insisting he’s spending huge sums of taxpayer money on defence. Every single government department has made cuts to fund next month’s defence investment plan (Dip), the prime minister promised, resulting in “the biggest sustained increase since the cold war”. On Sunday, the culture secretary, Lisa Nandy, told the BBC that cabinet ministers have been asked to look for further reductions to help fund defence.

Now squint and replace the word “defence” with “welfare”. Imagine Starmer – or any prime minister for that matter – boasting they’ve pinched cash from the NHS or schools to boost benefit payments. Indeed, swap “defence” for any sort of progressive cause – think housing, social care or net zero – and you’d be hard-pressed to picture a politician trying to save their career by pledging vast levels of spending, let alone if that spending was lifted from the Ministry of Defence (MoD).

Call it two-track governance, generously funding the military is seen as prudent and necessary but doing the same to improve the lives of ordinary people is wasteful and optional. Just look at how, when Wes Streeting criticised Starmer’s handling of the defence budget last week, he lamented the £4.5bn the government is set to spend on walking and cycling projects. That the former health secretarywill presumably be well aware such initiatives ultimately pay for themselves in improved public health outcomes just doesn’t fit with the narrative. A stronger military is an investment; a healthy and happy population is frivolous.

To question this double standard is not to say that there is not a good case for more defence spending. The world undeniably feels increasingly unsafe, with conflicts in the Middle East and Ukraine, and an irate Donald Trump in the White House. As if to prove the point, at the weekend, British armed forces intercepted a Russian shadow fleet oil tanker in the Channel.

The MoD also has a funding gap; latest figures show a £18bn black hole, of which the Treasury has found £13.5bn to plug. But in that way, defence is no different from any other government department – all of which have pressing needs and limited resources – and yet it rarely receives the same level of scrutiny. The smallest change to social security, for example, is greeted with endless incensed front pages, while ministers can spend billions of pounds on weapons without a single pundit debating the details.

Any slight diversion from this status quo – even by a figure such as Starmer, who just last year slashed the international aid budget by almost half to pay for a higher defence budget – is greeted, at best, with suspicion, and worse, outright hysteria. As the Daily Mail’s front page put it on Friday: “Britain left defenceless. God help us!”

It is not just that “progressive spending” is treated differently than defence expenditure – it’s that the two are increasingly pitted against each other. Within hours of John Healey resigning as defence secretary, Reform UK’s leader, Nigel Farage, took to social media to declare: “The government is happy to splurge vast amounts of money on disability benefits for those who don’t need them … and yet defence has gone back to the bottom of the pile.” Not to be outdone, the Conservative leader, Kemi Badenoch, has since written to the prime minister to offer to work together to reduce benefit spending to invest in defence for “the national interest”.

This welfare v warfare narrative has been building for some time. Earlier this year, the Centre for Social Justice thinktank released a study directly linking benefits and defence funding. The projected £18bn increase in welfare spending, it said, could pay for 15 advanced Royal Navy frigates, 220 fighter jets, or 250,000 soldiers’ salaries. The message is not exactly subtle: if it wasn’t for those scrounging disabled people, Britain could afford to keep itself safe.

Such framing is morally foul, of course, but it is also disingenuous maths. In order to meet the Nato target of dedicating 3.5% of GDP to defence by 2035, the Treasury would have to find an eye-watering £30bn in real terms every year for a decade. As context, in 2025/2026, the disability benefits bill was £77.1bn. In short, that means cutting welfare alone will not be enough to satisfy the defence hawks without catastrophic consequences for benefit claimants. It will require ongoing tax increases, borrowing, or – as is already being negotiated – taking more from multiple other already-squeezed government departments.

Which leaves us with two pressing questions. What does safety for a country in this era of instability actually mean? And how should a government spend its money to achieve it?

When Healey used his resignation letter last week to accuse Starmer of failing to allocate funds to keep the nation safe, I found myself thinking of the migrant care workers in Belfast hiding in their homes as racist rioters set fire to bus stops and bins outside.

There are many people in this country right now who could not be described as safe, but not because of Russia or Trump. There are the 3,000 NHS patients a day in England who – according to new figures – are being cared for in corridors, toilets and cupboards because there isn’t a bed for them in A&E. Or the fifth of British children “scarred” by long-term poverty, queueing in food banks or sleeping on the floor.

• Frances Ryan is a Guardian columnist