On the day that 4480 Army personnel were being declared redundant, Nato was handing over "security" in Afghanistan to the government of Hamid Karzai.

This was just after a suicide bombing in Kabul that had taken the lives of three human rights workers.

All but simultaneously, David Cameron was using the G8 summit at a golf resort in Northern Ireland to agitate for the arming of rebel forces in Syria. Set aside power politics, the attempt to isolate Russia, or hopes for a plan to end the fighting. The Prime Minister was laying off close to 4500 soldiers, 715 with no choice, while picking a side in a civil war.

You might hope for the day when all armies become redundant. You might also be confident that Mr Cameron has no intention of ever involving British forces in the fighting in Syria. You might even believe that something has been achieved in Afghanistan after 444 deaths on "our" side in a dozen years. The difference between Mr Cameron's behaviour on the world stage and military reality is stark.

His Government has been busy lately, after all, telling us that an independent Scotland would be defenceless in a terrible world without the military strength of the United Kingdom. One response would be that the wee country would have no taste for the military adventures that have bewitched recent British prime ministers. But some questions are practical, not theoretical.

Mr Cameron's Government means to cut the number of regular soldiers from 102,000 to 82,000 when all experience says "boots on the ground" can never be supplanted by drones, absurd aircraft carriers, or the kind of hellish nuclear kit on which the present Government and Labour are so keen. Yet the Coalition means to turn 20,000 soldiers into supply teachers, supposedly, while pressing on with Trident's replacement.

Any number of billions can and will be found for that project. Any amount of rhetoric can be summoned for 444 dead. No doubt the 715 "compulsories" will get some sort of vote of thanks from Mr Cameron and his ministers to see them into an uncertain future.

This is, nevertheless, an old and ugly British tradition, familiar since the Napoleonic wars. Like those being laid off this week, Rudyard Kipling knew it well enough:

"For it's Tommy this, an' Tommy that, an' 'Chuck him out, the brute!'

"But it's 'Saviour of 'is country' when the guns begin to shoot ..."

Can Britain manage with 82,000 regulars and an enhanced – so ministers promise – reserve? You could say that remains to be seen. Superannuated generals have been revising their calculations with the passing years. First we heard another Falklands would not be feasible. Then it was another Iraq. Through most of the 12 years in Afghanistan, British forces were stretched to the limit amid catastrophic failures of equipment and supply. Some died as a result. You could say we – whoever "we" happen to be – should not be involved in America's proxy wars. If so, you'd get my vote. The reality is that Mr Cameron is posturing as though Britain remains a major military power while cutting troop numbers and devoting resources to a weapons system he can never use. The disjunction is striking if not shameful.

Germany's Bundeswehr has a very well-equipped army of 62,279. That number does not include medical services or, conspicuously, the Streitkraftebasis, the Joint Support Service, with combat units attached. SKB has 46,822 personnel on its own account. Germany also has a 144,000 reserve to cover all services.

The French land army, with a relatively tiny reserve, meanwhile has 122,328 soldiers, including the Foreign Legion. The Italian army – all volunteers, it should be said – comes in at just under 109,000. Spain's professional army, currently in the throes of inevitable cost-cutting, has 61,300 troops and an 80,000 Civil Guard reserve.

A British Army with 82,000 personnel could be defined as a perfectly respectable force for a middle-ranking European power. Most people could live with that, most of the time. But most recent prime ministers have boasted of our defence spending and behaved as though the possession of nuclear missiles is equivalent to the possession of divisions ready to respond to a real crisis.

Germany, France, Italy and Spain have been reluctant to sign up for recent American wars. Among those on the right in British politics it has been fashionable to mock them for their scepticism. The Germans, famously a bunch of wimps, would not fly at night in Afghanistan. But the reality is this: Germany has a more formidable defence establishment than Britain with no pretensions.

Why do we persist? In part because the Ministry of Defence will give up anything, 715 experienced professionals not least, before it will give up its nukes. Politicians, equally, believe the Trident billions are a price worth paying for a UN Security Council seat. How any of this contributes to the defence of the realm is a point never explained.

It also leaves unanswered the fundamental question of Britain's "posture". On the one hand, we have politicians joined in a top-secret oath of loyalty to a foreign country. Mr Cameron's Syrian policy has as much to do with acting as a front for the White House as it has to do with any obvious British interest.

On the other hand, there are budget cuts which doubly decimate – if you count properly – the British Army and leave it incapable of backing up all the big talk. This is not what even a Coalition Government would call sustainable. It certainly does not count as common sense.

Would we rather have 715 professionals in work, never mind 4480, or some hugely expensive and useless programmes to fatten the bottom line for American defence contractors? Those professionals were trained, at no small expense, from the public purse. Some of them might turn out to be good school teachers. Nevertheless, as a defence policy, mass lay-offs insult the taxpayer as much as they insult the troops.

As it is, we have armed forces being shrunken to a decent European level while Whitehall continues to behave as though Britain is ready, on call, for the next American war. Yet the Falklands conflict was survived with a lot of luck. In Basra, British forces were humiliated. Afghanistan got a lot of ill-prepared people killed for no reason at a cost the country could not afford.

Mr Cameron is still pretending, as Tony Blair and Gordon Brown pretended, that Britain's affectations are matched by British defence planning. The black joke is that we are still spending vast sums, and certainly outspending our European counterparts, yet refusing to spend the money on those we expect to do the fighting and the dying.

Kipling, could he speak from the grave, would say that nothing changes. That's not entirely true. The world alters, but Britain's politicians remain the same. They differ from their European counterparts in one regard. Those terrible continentals tell the US military-industrial complex to do its own fighting and its own spying. Our elected representatives understand their divided loyalties differently.

Like all the generations before them, the 715 who have just been sacked will draw their own conclusions.