THERE is a traditional, gloating song of Paghman, some 30km from the Afghan capital, which dates from the British invasions of the 19th century: “Oh foreigner, do not attack Kabul, attacking Kabul is our job!” Today, a decade on from the western invasion that placed him in power, Hamid Karzai is often scornfully referred to as ‘the mayor of Kabul’ because, as in the bad old 19th-century days of bandit tribes, his mandate reaches barely outside the capital.

This year will be make-or-break for the West’s involvement in Afghanistan. President Obama has said that the United States will begin withdrawing forces by July, and control of security is due to be transferred from foreign to Afghan forces by 2014.

Parallel to the argument for military withdrawal, there is growing muttering — particularly from right-wing commentators in the US — about the extent to which the West should pour resources into the reconstruction of Afghanistan.

Nation-building is expensive and open-ended. Donor countries have pledged $67bn to Afghan development since 2002 (although only a fraction has arrived) and, while there has been some progress, western cash has also brought massive corruption. Last week’s brutal killing of UN workers following the burning of a copy of the Quran in Florida highlights how much a hostage to fortune any form of western involvement in Afghanistan can be.

Those who want to wash their hands of Afghanistan suggest that it is barely a nation anyway. Its geography is impossible — both a thoroughfare at the crossroads of Asia through which armies have historically trampled and a backwater of near-impassable mountains where the inhabitants of one village rarely meet those of the next.

Its society, too, is fractured — more than 30 languages are spoken, there are scores of ethnic groups and a religious divide that includes a Sunni-Shia split, tiny Hindu and Sikh populations and just one known remaining Jew. Not to mention what seems an incomprehensibly complicated collection of warlike tribes existing in a state of interdependence, rivalry and blood feud. No wonder the bogeyman of the US experience in Somalia is increasingly invoked.

And yet, despite its divisions and contradictions, I would argue passionately that Afghanistan is not like Somalia. It has integrity as a nation state, at least in the minds of its citizens. In 2009, for instance, in an ABC-BBC poll, 72 per cent of the population labelled their identity as Afghan first, before their ethnicity.

Afghanistan’s history as a modern state stretches back to 1747, when Ahmad Shah, a 25-year-old from Kandahar, showed his flair for working the tribal system at the Loya Jirga, the grand council. He was elected as leader of all the tribes. By 1751 his army had conquered the whole of present-day Afghanistan and annexed parts of India and Iran. In the process, he developed the concept of Afghaniat — ‘Afghanness’ — a kind of super-identity that transcends one’s family and tribal affiliations.

Since then nobody, from the British during the Great Game to the Soviet Union, has successfully colonised Afghanistan. And as the ABC News poll shows, the concept of Afghaniat is as strong as ever. Today, Afghanistan’s democratic parliament is based on the jirga system and is open to all ethnic groups. The massive turnout and optimism of the 2004 presidential elections; Abdullah Abdullah’s serious challenge to Karzai despite the shameful election fraud in 2009; the brave individuals who use parliament to condemn corruption and war crimes — all these were inconceivable during the dark days of the Taliban.

None of this would be possible without continuing western support. The population is traumatised by more than 30 years of war, which has claimed more than a million lives. People living in these circumstances can’t be expected to react moderately at all times, and the killing of the UN workers by anti-western insurgents shows that they do not. Is it then reasonable to expect them to rebuild a civil society without outside help?

The move to leave Afghanistan militarily makes it all the more important to support its political, educational, economic and physical infrastructure. Rebuilding Afghanistan will require a firm will, patience beyond belief and a long-term financial investment. But foreigners building roads and schools will always be more welcome than foreigners bearing guns. — The Guardian, London

The writer is a documentary film-maker; her films include Beneath the Veil.