In our increasingly destabilised present, it is difficult not to see echoes of the run-up to the first world war. Back then, a standoff between two great power blocs led to a fatalism that a disastrous war was simply inevitable. If history does indeed repeat itself, that would be catastrophic for two reasons. First, because the mass slaughter turned out to be the warm-up act for worse in the rest of the 20th century. In many ways, we are still living in the aftermath. Second, because such a repetition would in fact prove the best case scenario; a nuclear inferno that devours human civilisation is a more probable outcome. In two newspaper articles last week, Sir Keir Starmer committed Labour to retaining nuclear weapons and to hiking defence spending to 2.5% of GDP. Prevailing political wisdom would suggest this offers necessary distance from his predecessor, though it should be noted that Labour’s 2017 and 2019 manifestos both promised to retain Trident and keep defence spending to at least 2%, the target Nato members are committed to reach. But the truth is that this country cannot have a sensible discussion about defence. The Ministry of Defence is not far removed from George Orwell’s Ministry of Peace, given “defence” in practice has meant “offence”. Even though our media and political climates make these the policy and spending suggestions seem like utopian ideals, a truly rational approach would look rather different. First, we have to abandon creeping fatalism over a coming war. Over half of Britons think another world war is likely within the next five to 10 years, while 59% think nuclear weapons would be used if it breaks out. Mass resignation to nuclear annihilation strikes me as a problem. Such fatalism has been fuelled by top military officials declaring we must prepare for all-out war with Russia in the next two decades, while the defence secretary, Grant Shapps, calls for us to prepare for further wars involving China, Russia, Iran and North Korea within five years. Gen Sir Patrick Sanders, the head of our army, even calls for society to be placed on a war footing. Well, spare a moment for the unlucky survivors of a nuclear apocalypse who will be rather ruefully wishing more had been done to avoid their plight. More thought should be put into de-escalation, rather than repeating the pre-first world war error. Second, we must prevent a repetition of the calamitous 21st-century wars of “intervention”, which – in addition to destabilising Iraq, Afghanistan, Libya and others – killed 636 British service personnel (in Iraq and Afghanistan) and made us less safe. The UK intelligence services warned that “the threat from al-Qaida” and “other Islamist terrorist groups” would increase if Iraq was invaded, while we know the war in Libya played a pivotal role in radicalising the Manchester Arena bombings. Israel’s war in Gaza, framed by the UN as potential genocide, will surely prove one of the greatest mass radicalisation events of our age, and British complicity will expose us to the lethal consequences. It can hardly be said that these wars were about “defence”. Deterring terrorism is indeed a key plank of national security: abandoning offensive wars and support for mass slaughter is central to that. As for Trident, “the expense is huge and the utility … nonexistent in terms of military use”. Not my words: those of Tony Blair, who only renewed our nukes to maintain Britain’s pretence as a great global power. As Greenpeace put it in evidence to the House of Commons defence select committee: “The only way that Britain is ever likely to use Trident is to give legitimacy to a US nuclear attack by participating in it.” Britain is at no more risk of invasion than European nations that don’t fritter billions on warheads. Britain should pare back defence spending so it means just that: defence, or protection from invasion, assistance for humanitarian disasters, and international peacekeeping operations. As Richard Reeve, coordinator of the thinktank Rethinking Security, puts it, other “middle powers” – think Japan, Germany, Italy, Canada – don’t have global military pretensions. “Why do we believe we have a right and responsibility to act globally,” he says, “despite our resource constraints and legal norms?” That doesn’t mean producing only weapons for repelling hypothetical invasions: for example, supporting Ukraine’s defence against Russia’s brutal invasion is a legitimate example of arms exports, whereas the Saudi-led war on Yemen is not. That means producing significantly fewer weapons. Claims made about the economic benefits of the defence industry often intrude, but they are a mirage. As work by the thinktank Common Wealth reveals, despite defence production receiving on average 35% of UK public research and development funding between 1987 and 2009, defence adds less to the economy and employs fewer people than automotive manufacturing. Indeed, the sector offers rich rewards to asset managers and investment firms such as BlackRock, Vanguard and State Street, but if prosperity for local communities is what you want, then why is Barrow-in-Furness – where Britain’s nuclear submarines are built – so afflicted with poverty? What really happens is that the taxpayer shells out vast sums – between 2012/13 and 2021/22, the MoD offered up £78bn worth of contracts to its top five suppliers alone, while in the same period, those suppliers paid out £15bn to shareholders (based on their revenue from all global customers). It is true that Nato membership calls for arms spending of at least 2% of GDP, but in practice most states flout that. The real threats faced by Britain include pandemics – as you’ll probably recall – and cyber-attacks. Helping to stoke an arms race, and resigning ourselves to a future global conflagration, will hardly prove an effective means to protect our national security if it culminates in nuclear extermination. Focusing on actual threats, and ensuring we have a defence sector that can stave off a theoretical invasion, would be a more rational approach. What a tragedy that our political culture makes this almost impossible. This article was amended on 18 April 2024. An earlier version said that the House of Commons defence select committee concluded: “The only way that Britain is ever likely to use Trident is to give legitimacy to a US nuclear attack by participating in it.” The quote was in fact from evidence given by Greenpeace to the House of Commons defence select committee. Owen Jones is a Guardian columnist