Pakistani soldiers and an army helicopter in Sararogha, a former Islamist stronghold in South Waziristan 

Not since the demise of Marxism has the world been faced with a comprehensive political, social and economic ideology determined, by force if necessary, to achieve hegemony over large parts of the world. I mean, of course, the rise of radical Islam, in its various manifestations, with its claim to be the only authentic interpretation of the religion. I am aware that there are many Muslims who reject such an interpretation of their faith and, indeed, there are secular forces in the Muslim world prepared to resist such programmatic extremism. We should not, however, underestimate Islamism's capacity for disruption and destruction and its desire to remake the world in its own image.

In the face of such an ideology, the international community must not lose its nerve. Any withdrawal from a political, military and even intellectual engagement will be seen by the Islamists as capitulation. Instead of leading to containment, it will only encourage even greater attempts at the expansion of power and influence of movements connected with this ideology. This has already caused and will continue to cause immense suffering to those who do not fit in with an Islamist worldview, including minorities of various kinds, emancipated women and Muslims with views different from those of the extremists. The independence of nations, the autonomy of communities, traditional devotional practices (such as those associated with Sufism) and "deviations" from the prescribed orthodoxy will all be threatened, even with regard to their very existence.

It is true that this ideology, and the movements associated with it, thrive on the grievances, sometimes genuine, which Muslims have, whether in Israel/Palestine, Kashmir, Chechnya or the Balkans. Let there be no mistake, however, that the ideology exists not because of such grievances, but because of particular interpretations of Islam and what follows from them. There is a desire to purify the Dar al-Islam (the House of Islam) of all infidel influence and corruption. This means that the role of women must be greatly restricted, that non-Muslims must accept the inferior status of dhimmi (rather than that of fellow-citizens), if they are to survive at all and that even Muslim males must behave according to the dictates of the guardians of the ideology. The non-Muslim world (Dar al-Harb, the House of War) must be brought within the ideologues' sphere of influence, whether through persuasion, accommodation by others of the extremists' agenda or the fear of armed conflict.

The jihad, for these ideologies, cannot have the meaning of self-defence which so many moderates claim for it. It must extend not only to the recovery of the "Muslim lands" of Palestine, India, the Iberian peninsula, parts of the Far East and Central Asia and, indeed, many areas in Sub-Saharan Africa, but further than that, so that either through the dawa (the invitation to accept this version of Islam) or political and military means, more and more of the Dar al-Harb will become the Dar al-Islam. The fact that many Muslims do not share these aspirations, and may reject them, should not blind us to the reality that these Islamist ideologies do have them and are prepared to act on them.

The West's (particularly Britain's and America's) involvement in Afghanistan (and to some extent also in Iraq) must be seen in the light of what has been said above. There should be no facile optimism that al-Qaeda has been disabled and no longer poses a credible threat to Western or other countries. It is perfectly possible, given the right conditions, for al-Qaeda to resume being a potent force. It is also the case that the ideology associated with this movement is producing mutant groups such as al-Shabab in Somalia.