At least the Pentagon understands that the resistance in Iraq is following a familiar anti-colonial pattern. In the movie, they would have seen acts carried out by the Algerian maquis almost half a century ago, which could have been filmed in Fallujah or Baghdad last week. Then, as now, the occupying power described all such activities as "terrorist". Then, as now, prisoners were taken and tortured, houses that harboured them or their relatives were destroyed, and repression was multiplied. In the end, the French had to withdraw.

As American "postwar" casualties now exceed those sustained during the invasion (which cost the Iraqis at least 15,000 lives), a debate of sorts has begun in the US. Few can deny that Iraq under US occupation is in a much worse state than it was under Saddam Hussein. There is no reconstruction. There is mass unemployment. Daily life is a misery, and the occupiers and their puppets cannot provide even the basic amenities of life. The US doesn't even trust the Iraqis to clean their barracks, and so south Asian and Filipino migrants are being used. This is colonialism in the epoch of neo-liberal capitalism, and so US and "friendly" companies are given precedence. Even under the best circumstances, an occupied Iraq would become an oligarchy of crony capitalism, the new cosmopolitanism of Bechtel and Halliburton.

It is the combination of all this that fuels the resistance and encourages many young men to fight. Few are prepared to betray those who are fighting. This is crucially important, because without the tacit support of the population, a sustained resistance is virtually impossible.

The Iraqi maquis have weakened George Bush's position in the US and enabled Democrat politicians to criticise the White House, with Howard Dean daring to suggest a total US withdrawal within two years. Even the bien pensants who opposed the war but support the occupation and denounce the resistance know that without it they would have been confronted with a triumphalist chorus from the warmongers. Most important, the disaster in Iraq has indefinitely delayed further adventures in Iran and Syria.

One of the more comical sights in recent months was Paul Wolfowitz on one of his many visits informing a press conference in Baghdad that the "main problem was that there were too many foreigners in Iraq". Most Iraqis see the occupation armies as the real "foreign terrorists". Why? Because once you occupy a country, you have to behave in colonial fashion. This happens even where there is no resistance, as in the protectorates of Bosnia and Kosovo. Where there is resistance, as in Iraq, the only model on offer is a mixture of Gaza and Guantanamo.

Nor does it behove western commentators whose countries are occupying Iraq to lay down conditions for those opposing it. It is an ugly occupation, and this determines the response. According to Iraqi opposition sources, there are more than 40 different resistance organisations. They consist of Ba'athists, dissident communists, disgusted by the treachery of the Iraqi Communist party in backing the occupation, nationalists, groups of Iraqi soldiers and officers disbanded by the occupation, and Sunni and Shia religious groups.

The great poets of Iraq - Saadi Youssef and Mudhaffar al-Nawab - once brutally persecuted by Saddam, but still in exile, are the consciences of their nation. Their angry poems denouncing the occupation and heaping scorn on the jackals - or quislings - help to sustain the spirit of resistance and renewal.

Youssef writes: I'll spit in the jackals' faces/ I'll spit on their lists/ I'll declare that we are the people of Iraq/ We are the ancestral trees of this land.

And Nawwab: And never trust a freedom fighter/ Who turns up with no arms/ Believe me, I got burnt in that crematorium/ Truth is, you're only as big as your cannons/ While those who wave knives and forks/ Simply have eyes for their stomachs.

In other words, the resistance is predominantly Iraqi - though I would not be surprised if other Arabs are crossing the borders to help. If there are Poles and Ukrainians in Baghdad and Najaf, why should Arabs not help each other? The key fact of the resistance is that it is decentralised - the classic first stage of guerrilla warfare against an occupying army. Yesterday's downing of a US Chinook helicopter follows that same pattern. Whether these groups will move to the second stage and establish an Iraqi National Liberation Front remains to be seen.

As for the UN acting as an "honest broker", forget it - especially in Iraq, where it is part of the problem. Leaving aside its previous record (as the administrator of the killer sanctions, and the backer of weekly Anglo-American bombing raids for 12 years), on October 16 the security council disgraced itself again by welcoming "the positive response of the international community... to the broadly representative governing council... [and] supports the governing council's efforts to mobilise the people of Iraq..." Meanwhile a beaming fraudster, Ahmed Chalabi, was given the Iraqi seat at the UN. One can't help recalling how the US and Britain insisted on Pol Pot retaining his seat for over a decade after being toppled by the Vietnamese. The only norm recognised by the security council is brute force, and today there is only one power with the capacity to deploy it. That is why, for many in the southern hemisphere and elsewhere, the UN is the US.

The Arab east is today the venue of a dual occupation: the US-Israeli occupation of Palestine and Iraq. If initially the Palestinians were demoralised by the fall of Baghdad, the emergence of a resistance movement has encouraged them. After Baghdad fell, the Israeli war leader, Ariel Sharon, told the Palestinians to "come to your senses now that your protector has gone". As if the Palestinian struggle was dependent on Saddam or any other individual. This old colonial notion that the Arabs are lost without a headman is being contested in Gaza and Baghdad. And were Saddam to drop dead tomorrow, the resistance would increase rather than die down.

Sooner or later, all foreign troops will have to leave Iraq. If they do not do so voluntarily, they will be driven out. Their continuing presence is a spur to violence. When Iraq's people regain control of their own destiny they will decide the internal structures and the external policies of their country. One can hope that this will combine democracy and social justice, a formula that has set Latin America alight but is greatly resented by the Empire. Meanwhile, Iraqis have one thing of which they can be proud and of which British and US citizens should be envious: an opposition.

· Tariq Ali's new book, Bush in Babylon: the re-colonisation of Iraq, is published this week by Verso