Two.

All wars have anthems for doomed youth. Afghanistan is no exception. At a memorial service yesterday, senior officers paid tribute to the eight British soldiers who died in the worst day of attrition since the Falklands.

Of the three youngest, William Aldridge had a gift for friendship, Joseph Murphy was a fine artist and James Backhouse, who wanted to be a fitness instructor, could run faster than the wind. Like his two comrades, he was 18 years old. Like them, he was, according to his superiors' eulogies, prepared to kill and to be killed.

Helmand province is not the Somme, but Wilfred Owen's lament for squandered life has seemed, back in the UK, to echo down the years. "What candles may be held to speed them all?/Not in the hands of boys but in their eyes/Shall shine the holy glimmers of goodbyes."

Owen blamed the state for sacrificing the young. Now, once again, government is deemed culpable as every parent sees, in the faces of the juvenile dead, an image of his or her own child. "What passing-bells for these who die as cattle?" Owen asked.

Almost a century later, there is no shortage of funeral hymns. Liam Fox, the shadow defence secretary, says Gordon Brown has "catastrophically" under-equipped the Armed Forces. For the Lib Dems, Nick Clegg challenges the PM to show the sacrifices of lives "have not been in vain". The Army demands extra troops and more equipment.

With the Taliban getting smarter and 15 British troops dead so far this month, Afghanistan is a dimestore war. In four decades, the defence budget has fallen from 6.5 per cent of GDP to 3 per cent, while Tony Blair's imperial ambitions committed troops to four major conflicts, of which Iraq was inexcusable and Afghanistan, on the current showing, unwinnable.

Mr Brown's critics imply that he is trying to fight a Prada war at Lidl prices. Although he disputes this, defence spending is undeniably out of kilter with reality. The PM's likely concession on Trident – cutting back on warheads and perhaps reducing the new fleet – is a feeble compromise that will not free up significant sums for the frontline. Nor is it likely that taxes will rise to boost defence.

But even if a war chest were to be found, there is little clarity about what we're fighting for: the end of brutal and repressive Taliban mandates or, as Mr Brown says, to stop terror being exported to the UK. With al-Qaeda moving sinously across the globe, the second goal looks hopeless.

The real question is whether the Afghan war can ever be won by military means alone, and the answer, as David Miliband has always recognised, is No. In stirring up trouble for the Government, the generals and the Tories risk peddling a delusion. Yes, extra helicopters may save some lives (though by no means all), but the truth about Afghanistan risks being obscured by political opportunism. Even vast injections of money, hardware and manpower would not, by themselves, subdue the Taliban or procure victory.

A political solution is the only guarantee of success, yet that objective is barely spoken of. In the US and the UK, next month's presidential election attracts almost no mention. Since the temporary increase in British troops is specifically to provide cover for the ballot, this silence is suspicious, if not downright sinister.

The appalling regime of Hamid Karzai is western leaders' grubby little secret. Mr Karzai, who boasts of being Washington's (and thus Britain's) man, presides over the fifth most corrupt government in the world. As well as turning a blind eye to last year's alleged loss, through abuse, of two thirds of his country's annual revenue amounting to $1.6 billion, Mr Karzai has failed the vulnerable and the trusting.

Naturally, Western leaders cannot impose an alternative placeman to sort out his narco-state. But, in a field of around 40 challengers, two credible candidates stand out. One, Abdullah Abdullah, is the former foreign secretary; the other, Ashraf Ghani, is the one-time finance minister and former chancellor of Kabul University.

Although Dr Ghani, once tipped to become UN Secretary General, has the only coherent agenda and a well-orchestrated e-campaign, the odds are greatly against him, and other contenders, because the election commission is stacked with Mr Karzai's henchmen.

Disgracefully, neither Washington nor London has publicly demanded a level playing field or complained that the election for which British soldiers are dying is effectively rigged. Meanwhile, Dr Ghani, who has no official protection, is making a swift transition from Washington technocrat to politician. His billboards in Mr Karzai's home town of Kandahar have been vandalized with acid and removed; supporters in Britain say he is putting his life at risk.

Until a few days ago, it looked impossible that Dr Ghani would ever institute his 10-year framework enshrining the rule of law, good governance and co-operation with local groups and the international community. But suddenly, Washington is growing nervous. As chilly signals about Mr Karzai reach Kabul, the president is hiding in his palace, declining to appear on the campaign trail or debate on television with his rivals.

Educated voters, informed by independent TV and radio, are disgusted by his pardon of drug-dealers and his ties to militia leaders. The UN and the Afghan human rights commission have logged many complaints about state interference in the election amid a dawning hope that Mr Karzai may not win outright in the first ballot. If he fails on August 20, then his network of powerful allies may collapse, leaving either of his main rivals a chance of victory.

Should Mr Karzai cling to power, which is still much the likeliest outcome, then it is just conceivable that the US "surge" will be enough to broker a deal with the Taliban. More probably, corruption will continue and insurgents will gloat at the prospect of a long war whose history will be written in British blood.

Our government must urgently address national security and the misfit between yesterday's under-funded defence strategy and today's myriad dangers. As Professor Paul Rogers, of Bradford University, says, the colonial era ended in 1947 with the partition of India. Mr Blair failed to notice the shift, and Mr Brown is left to pick up the pieces.

The omens could hardly be grimmer. Not only are the military objectives hazy, but a campaign costing $20 billion a month has no political direction. Voters here, as in Afghanistan, deserve the truth. We are pouring blood and money into a black hole, and the flow will not be staunched unless a political solution is found.

Until then, 18 year-olds with the fresh faces of your sons, or mine, will fight and fall. They do not require passing-bells, or candles; only good equipment and the guarantee that they are the brave architects of a better future. No civilised nation should ask its soldiers, young or old, to die for less.