You might think that the fall of Kabul to Taliban forces last weekend was the worst possible outcome for the US and NATO after twenty years. But while there is instinctive support in the West for the anti-Taliban resistance (currently called the National Resistance Front of Afghanistan), which says it has thousands of people ready to fight, this may not be in the West’s interests. We want them to put up a stand, and we hope that they will rout the Taliban. But this seems very unlikely at the moment, and a contested Afghanistan, with unending skirmishes, could be much, much worse.

There are some obvious reasons why: Afghanistan badly needs stability – a government which is able to administer the country, to enable the operations of the NGOs which have provided humanitarian aid since 2001. There is a clear imperative, for the sake of the Afghan people, for this to continue, but it will be fraught with physical risk and moral complexity. However ghastly and unthinkable, a Taliban-run Afghanistan which is recognised by some nations, which has a relationship of sorts with the United Nations, which wishes to engage to a limited extent with global infrastructure (a banking system, the Internet) will be significantly safer for any foreign aid organisations to operate within than a still contested one.

But there is another reason why some stability might be better than endless contest. Imagine if Jihad in Afghanistan became again a rallying call for Mujahideen the world over – to come and defend the Taliban’s victory? Attention has so far focused on whether the Taliban will allow Al-Qaeda to come back (they never actually left), and whether terrorist groups will be able under Taliban control to use it as a base to plan and project attacks against the west (probably sooner or later). But a contested Afghanistan would draw a new generation of defenders of the faith to rally behind the black and white flag in the land of Khorasan, a geography which stretches from eastern Iran across parts of Afghanistan. Khorasan has a special resonance for Islamist fighters because of an apocalyptic Hadith which states that ‘there will emerge from Khorasan black banners which nothing will repel until they are set up in Jerusalem.’ If we think that the Taliban victory has given a morale boost to Jihadis the world over, think what a cause would be created if the Taliban seemed under threat again.

This could pose a particular challenge for the UK, with its Pakistani-Kashmiri diaspora community (there are over a million British Pakistanis, the second largest ethnic minority population in the UK; the majority come from Mirpur in Azad Kashmir and the Punjab). Within Pakistan there have been strong Kashmiri links to the Taliban and Al-Qaeda from the beginning: the terrorist group Lashkar e-Taiba, which carried out the Mumbai attacks in 2008 killing 166 people, was founded in Afghanistan in the late 1980s, allegedly with funding from Usama bin Ladin. Its founder, Hafiz Saeed, was close to Usama bin Ladin’s mentor Abdullah Azzam. One of the masterminds of the Mumbai attacks, Zaki ur Rehman Lahkvi, led a group of anti-Soviet Jihadists. It is reported that LeT have been fighting alongside the Taliban in Afghanistan and are manning Taliban checkpoints. Like other terrorist groups, LeT has a political wing, Jamaat ud-Dawa, which is popular in the Pakistani Punjab and in Azad Kashmir and provides charitable and cultural support.

When Daesh proclaimed the establishment of a Caliphate in Iraq and Syria and made it the duty of believers around the word to join their Jihad, western countries made travel to Syria very difficult, and kept a record of those they knew had travelled out to Syria. It will be significantly more difficult to monitor travel to Pakistan/Afghanistan, not least because of the sensitivities of doing so for dual nationals (with the very real risk of judging or stigmatising a new generation). Approximately a quarter of a million British citizens visit Pakistan every year, largely to visit family. But in the 1990s and 2000s a few of them went to join the Kashmiri Jihad, and a few of them went to join Al-Qaeda. The lure of the Taliban cause, particularly if it were threatened, will be tempting for a small number, and particularly so if they already have connections in the country. Some British Jihadis have much closer allegiances to the Kashmiri groups than they ever did to Daesh.

An additional issue to watch is the branding competition between the Taliban and Daesh-Khorasan Province (Afghanistan branch). The Taliban are the old guys and Daesh the less established but still resilient new kids on the block. They do not get along. So far Daesh’s messaging has sought to undermine the Taliban’s position by saying that the Emirate is less legitimate than the Caliphate. The Taliban have the numerical advantage, but they will come to blows. A better outcome in the circumstances would be for the Taliban to rout the newcomer quickly. There are two potential bad outcomes: for the two to reach a deal, or for the battle to last longer, with Daesh flags drawing in fighters from across the Middle East to take territory in Afghanistan.

This all feels unthinkable: we definitely wouldn’t wish to start from here. But now we are here, we need to consider how things might unfold. An unintended consequence of a new fight might be a new generation of fighters.