For Britain, 3 per cent would mean eye-watering spending increases of tens of billions of dollars a year; this represents the largest increase since the Korean War in the early 1950s.

Tusa said the UK, despite nominally sitting high in NATO’s league table, was seen as a “laggard” on defense spending and would face difficult choices to adapt.

“Finland, Poland, the Swedes; they’ve all increased their defense budgets significantly,” he says. “And meanwhile, in Sweden, social security is being cut to pay for this.”

Lord Stirrup, a former RAF marshal who was chief of the defense staff from 2006 to 2010, described the debate last month on whether to raise spending to 2.5 per cent or 3 per cent of GDP as “one should use two or three fire extinguishers during building construction”. He likened it to “deciding whether to buy it or not”. “It burns around your ears.”

“We face a double challenge,” he warned ministers in a House of Lords debate. “We must compensate for the shrinking and hollowing out of our Armed Forces caused by successive, criminal governments.

“At the same time, we need to adapt these forces to meet the stark and urgent challenges of the future.”

He added that the last year the UK spent a similar amount on defense was 2010, “at a time when Europe was not facing a serious threat from Russia”.

“The mantra seems to be that there is no more money. Of course the money is available; “It’s a matter of choices and priorities.”

To defend themselves, NATO member states will need to increase capabilities that have been allowed to deplete and restock large quantities of ammunition, tanks and other materiel. they already gave it to Ukraine.

This process is already ongoing. BAE Systems, the UK’s largest defense company, has reported a £25bn increase in orders this year alone.

But industry executives warn that turning the taps back on after years of using the “peace dividend” to finance other priorities, such as welfare and health spending, will not produce immediate results. The pace of rearmament of NATO member states will be constrained by factory capacity and resources.