It speaks volumes about the world today that a US president was more worried about the Taliban looking weak than about his western allies. Britain, France and Germany asked Joe Biden to continue evacuating civilians from Kabul past his self-imposed deadline of 31 August. But the US rejected these requests. Mr Biden wanted to end the chaotic TV scenes from Afghanistan that hurt his domestic poll ratings. But he also accepted that Kabul’s new rulers could not afford to look weak in front of their rival Isis, which is looking for an opportunity to embarrass its Taliban peer.

The west’s airlift will therefore be over by next Tuesday. It is the Afghan people who will pay the highest price for the west’s defeated ambitions for their country. They now face living under Taliban rule for a second time. There is no guarantee that a grinding civil war is over. The scale of the west’s failure is not just that the world’s biggest economies will almost certainly fail to evacuate all those who were employed by its armies and diplomats. It is that we have let down a generation of urban Afghans, especially women, who grew up believing that their lives would be better than their parents’.

Afghanistan faces a series of crises that would tax the most able technocrats. Yet at the country’s helm is the world’s most obscurantist leadership. Covid has a long way to run in Afghanistan, but only 2% of the population has been vaccinated. The Taliban struggle with the idea of female doctors working in hospitals, let alone how to tackle coronavirus. A drought has caused famine in rural parts of the country, but Afghanistan’s new rulers see humanitarian work as the preserve of charities rather than the state.

The Taliban have no experience of legislating within a sophisticated political and legal framework, especially one of the kind modelled on western democracies. When they last ran the country, a cash economy did not exist. In the Afghan central bank, more than two decades ago, the Taliban installed military commanders. One died on the battlefield while still the bank’s governor.

The west’s economic model for Afghanistan was, at best, a work in progress. The country has become dependent on international assistance, while poverty rates have increased from a third of the population to more than a half. Unless something extraordinary happens, foreign aid will dry up, leaving the Taliban not only unable to pay for government salaries but also without the resources to cover Afghanistan’s import bill. With the US refusing to hand over Kabul’s dollar reserves, the Afghan currency is likely to collapse in value, sparking a price spiral. Inflation and scarcity are not exactly solid foundations on which to base the stability of a regime.

One cannot import development, only encourage it from within. Two Asian countries that have risen by throwing off outside rule – Vietnam and Bangladesh – show that it is possible to wean a country off foreign aid in a substantial way by creating an industrial base. The new Kabul regime is more likely to fall back on opium production, confirming its global pariah status while further diminishing the nation’s productive capacity.

Afghanistan’s complexity – its patchwork of ethnicities, traditions and minimal governance – makes it hard to understand. The G7 might be able to use a carrot-and-stick approach with the Taliban. It could offer cash in return for the group respecting human rights or threaten sanctions if Kabul breaks promises. The world, ultimately, will have to adjust to American interest in Afghanistan assuming more conventional proportions. Washington, in the future, will monitor jihadist threats from afar and seek to preserve political balance in Kabul. What has disappeared is the latest attempt to impose a new Afghan society on top of an old one.