Leaving is the easy bit. It’s the looking back that hurts. There was – as Joe Biden pointed out when announcing America’s defeat at the hands of the Taliban on 31 August – nothing “low-grade or low-risk or low-cost” about a 20-year deployment that cost the United States more than $1tn and thousands of service personnel their lives, their limbs or their peace of mind. But it is disingenuous to claim, as the president also did, that closing the door on Afghanistan will miraculously free the US to deal with more pressing concerns such as China and Russia. A humanitarian crisis looms over the country, caused in part by the abrupt halting of international aid after the Taliban takeover. Even now, despite the US retreat and the announcement by the regime, on Tuesday, of an interim cabinet that gives scant representation to the country’s different ethnic groups and none at all to women or Shias, Afghanistan can’t be forgotten. Its people’s needs, and the country’s capacity to send out ripples of instability, will continue to demand attention. Until August, the US and others, including Britain and the EU, had donated tens of billions of dollars in development money to the country. Since the return of the Taliban to power, this aid has been cut off. The US also froze about $9.5bn in Afghan assets held in American banks. Legally, the decision was justifiable; the Taliban remain under international sanctions. But morally and politically, it stank. The aid money that has now been stopped pays the bureaucrats, doctors and teachers who have given Afghanistan glimpses of a functioning society – the very people whom Biden promised to support even after withdrawal. And it is these Afghans who now face oblivion. On 1 September, António Guterres, secretary-general of the United Nations, tweeted that basic services in Afghanistan are close to “collapsing completely”. There is no money for wages, food prices have soared and a run on the banks was only prevented by limiting weekly withdrawals to $200. With 550,00 people displaced by Taliban offensives this year alone, Covid-19 wreaking havoc – less than 3% of Afghans have been vaccinated – and the country suffering its worst drought in decades, the abrupt cessation of aid is more than the country can bear. At the start of month, the US licensed its own contractors to send food and other essentials to the country. The EU and Britain are exploring the possibility of transferring emergency funds directly to NGOs on the ground, bypassing the Taliban. The west is making the resumption of inflows for development – health infrastructure, for instance, or toilets for schoolgirls – conditional on the Taliban not only rejecting terrorism but also doing an about-face and espousing equal rights for women and religious minorities. This might seem like a big ask for a theocratic organisation wedded to a medieval ideology and that, with the reported capture of the symbolically important Panjshir valley, claims mastery over the whole country. But the US and its allies hold a precious card. The Taliban may be divided – between battle-hardened field commanders and their leaders who spent years in comfortable exile; between pragmatists who will tolerate girls attending school and hardliners who abhor the very notion – but on one thing they all agree, and that is that their revived emirate deserves international recognition. The question now is whether Biden remains interested enough in Afghanistan, this faraway place of which Americans know little, to use his leverage effectively. Estrange himself irrevocably from the Taliban and they can reverse with impunity the tangible advances that Afghan society has made over the past 20 years. For support they will turn to China and Russia – both of which have maintained embassies in Kabul and also left their names off a recent UN security council resolution calling for the Taliban to form a broad-based government upholding human rights. For cash they will plant more poppy and to advance their agenda they will cooperate with al-Qaida and the more unsavoury elements of Pakistan’s security apparatus. Each crisis in this landlocked country begets one abroad. Memories of the Syrian refugee influx of 2015 lie behind the EU’s anticipated offer of €600m (£515m) for Afghanistan’s neighbours towards hosting the refugees who are expected to stream out of the country. “Building a moat,” as one Afghan NGO leader told me, “to stop them heading west.” Time is of the essence if the immediate balance of payments crisis is not to balloon into a catastrophe. The Americans and Europeans must exploit every legal loophole to get aid into the country. In this they will find willing partners in those international NGOs that enjoy highest prestige among ordinary Afghans, and which, through judicious handling of Taliban officials in the country’s far-flung provinces, enjoy cooperative relationships with its new rulers. This is the kind of aid that works: projects like those of the Aga Khan Development Network, the Bangladeshi NGO Brac and the International Rescue Committee that pride themselves on assisting Afghans to meet their own demands – for piped water, for instance, a clinic for young mothers, or a fruit tree nursery – employing mainly locals, watchful of waste and corruption, and working with whoever is in power. With the Taliban’s leaders, the US and its allies must use the tantalising prospect of legitimacy – not recognition; it is too early for that – to exact more than the vague promises of a free media, women’s rights and respect for minorities they have received to date. The Afghan regime that fell last month was a kleptocracy that has cleared out with its loot. The Taliban’s new regime will be horrendous in other ways. But it controls the country, it needs money and legitimacy, and its behaviour can be influenced. That, as Biden surveys an old, wrecked policy and reluctantly contemplates a new one, is a start. Christopher de Bellaigue is an author and journalist. His forthcoming book, The Lion House, is the first in a trilogy about Sultan Suleyman the Magnificent