This is, indeed, what happened. The Soviet threat was contained and, in fact, led to the dismemberment of the Soviet Union itself but, since then, extremist Islamism has flourished both in the region and more widely than that.

As General Secretary of the Church Missionary Society (CMS), I worked closely with the local churches in supporting the vital work of hospitals, founded by CMS, all along the long Pakistan-Afghan border serving the neediest people of both countries. They will, undoubtedly, be needed again.

From such a long association with the region, what has struck me most forcibly this time is the way in which the American-led West has simply abandoned a society it has helped to create. The oft-heard nostrums of politicians, that the West had gone in simply to avenge Al Qaeda's attack on 9/11 and to make sure it never recurred again, ring hollow. The establishing of a culturally appropriate form of democracy, encouraging and funding civil society, female education and much else besides was not extra to the task of eradicating the threat of regional and international terrorism from the soil of Afghanistan, but integral to it.

Will nations, for example in the Indo-Pacific area, even now being garnered to protect the West's interests there, ever again be able to trust the West? When, they will ask themselves, will they be told that Western self- interest no longer needs their friendship? The unilateral American decision to withdraw all troops is morally irresponsible, as is collusion with it by other Western powers, even if some, like Britain, had reservations about it.

It seems to me, that the least that could have been done was to have made withdrawal conditional on a comprehensive peace agreement between the government in Kabul and the Taliban. Without such an agreement, withdrawal is tantamount to handing over large sections of the Afghan people to the whims of a movement known for its past and present brutality.

Sensing blood, the vultures are circling: ISIS is active already, and not only in the remoter parts of country. We can be sure that others like Al Qaeda and the notorious Haqqani Group, for long allied with the Taliban, cannot be far behind.

The resurgence of extremist Islamism on Afghan soil has significant implications for the region. The Central Asian nations, consisting of the former Soviet republics, are terrified of Taliban infiltration, and will become even more draconian in their determination to stamp out what they see as extremism. Most of them remain within the Russian circle of influence and Russia also needs to make sure its own southern flank is not radicalised further.

China, similarly, has become alarmed at what it sees as extremist influence permeating its Western region of Xinjiang and we can expect a further tightening there of the plight of the Uighur ethnic group. The security situation in Pakistan has greatly improved of late, but the Afghan Taliban owe a great deal to safe havens provided by radical groups in Pakistan. There will certainly be 'quid pro quo' demands for them now to find hospitality in a Taliban-controlled Afghanistan. What will be the implications of such cross border bases for security in Pakistan? I am not holding my breath.

Within Afghanistan itself, there is the possibility of civil war with Northern Dari speaking tribal groups and their leaders (sometimes misleadingly called 'warlords' in the West) likely to resist the Pashtun-led Taliban and their interpretation of Shari'a. Civil and military chaos, if not Taliban complicity, will surely result in the country, once again, becoming a base for extremist violence not limited to the region. If and when this happens, the West's decision to withdraw unilaterally and unconditionally will begin to look not just morally weak but strategically foolish.

In the meantime, American female journalists in Afghanistan donning hijab and chador to report is a sign of what is coming for Afghan women and girls. Women have already been told to wear the burqa (the all enveloping veil which covers the face) or to wear the niqab (a face mask) and gloves in any public appearance. They will not be allowed to work with men and their access to education, especially higher education, remains in doubt. All the gains made by them in the professions, in public life and in civil society could be just wiped out as they were when the Taliban were last in power.

The situation of religious minorities is also parlous. The minority, and largely Shi'a, Hazara have already declared that they are facing genocide. My post bag and reports from aid agencies bear witness that Christians, Sikhs and Hindus are desperate to flee and the rich Buddhist heritage of the Gandhara Indo-Hellenistic civilisation is again in jeopardy.

The reimposition of Shari'a penal law could bring us the spectacle of public executions, mutilations and floggings, sometimes for minor offences like violating the strict dress code, petty theft or 'obscene' entertainment like mixed dancing, even in private.

Britain, of course, needs to honour its obligations to those who assisted its mission in Afghanistan but, in the face of such an apocalyptic situation, there must be urgent international agreement about the flood of refugees that is likely to result from a Taliban takeover

Europe should not be left to bear the brunt of such a mass movement, as it was with the war in Syria. North America, Australasia and the Organisation of Islamic Cooperation must all take their full share of refugees. A condition of any recognition of a Taliban-led government should be respect for fundamental freedoms, especially for women, girls and religious and ethnic minorities. The Taliban should accept UN and other accredited rapporteurs to monitor and report on the human rights situation in Afghanistan from time to time. Such monitoring and reporting will include not only the condition of groups like women and minorities, but also matters like respect for the person in the application of penal law and the withholding of inhumane and degrading punishments. The rapporteurs must have access to the country and to the groups they are monitoring.

Many of these measures, whilst urgent and necessary, are but bandages for a wound which will take much time to heal. In the longer term, the aim must be the promotion of a culturally appropriate democracy, adherence to the UN Declaration on Human Rights, particularly Article 18 which deals with freedom of belief and expression, and guarantees regarding female access to education and employment. We must ensure, now western troops are home, that the world does not forget the vulnerable in Afghanistan and that may mean a majority of the population.

Bishop Michael Nazir-Ali was Bishop of Rochester for 15 years. He is originally from Southwest Asia and was the first Diocesan Bishop in the Church of England born abroad.