Support for the Anglo-American war on Iraq must now rank as one of the most comprehensively humiliated political positions in recent history. The original reason given for the invasion, essentially self-defence, was always ludicrous. But even the details of that "thin" justification - the supposed WMD threat - have now been dragged through the mud and exposed by the declassified record as a PR stunt "got up" by the aggressor nations to sell the "inevitable" war. (quoting the views of the British Foreign Secretary and other senior officials).

The subsequently altered official justification - humanitarian intervention - was as plausible as the supposed military threat Baghdad posed to London and Washington. The nations that backed Saddam whilst he committed all his worst atrocities, that killed over a million Iraqis with sanctions, half of those children under five, had in fact, we were told, intervened in Iraqi affairs out of altruistic concern for its people. Those nations launched a war that according to the best estimates available has killed well over 100,000 Iraqis in order to bring them prosperity, freedom and all the other rewards of western benevolence that the third world has enjoyed over the past five centuries. With the added element of the occupier's sheer incompetence (resulting in one of the great military fiascos of modern history), the welfare of Iraqis progressed even beyond the levels one could have expected. Anarchy, terrorism and counterinsurgency warfare ran riot. Child malnutrition and infant mortality rocketed (from the level that killed half a million infants under sanctions) as sewage flowed in the streets and the economy collapsed. Iraqis were rounded up and subjected to vicious sexual torture, often in the prisons of the coloniser's former client dictator. Iraqis can at least console themselves with their new found right, wrested from the occupiers, to vote, in unmediated elections where campaigning is impossible for politicians whose hands are bound by the occupiers in any case. This right may even be exercised by those lucky enough to dodge gangs of kidnappers, terrorist explosions, the occupier's bullets and the foreign airforce that still bombs Iraq's towns and cities. This is the result of two and a half years under the protective wing of the US and its British lapdog.

Plainly fresh reasons for the colonisation of Iraq are required. Now we are asked to believe that the occupation must continue until order is restored, as though the disease will, at some future date, magically transform itself into the cure. Sectarian killings and general lawlessness, we are warned, will overrun the country if our troops are not on hand to save the Iraqis from themselves. This of course ignores the fact that these very things have come to pass already in the new Iraq which we have generously created. Withdrawal will come, our leaders promise, when the security is restored, when the occupation has precisely the opposite effect from the one it has had since 2003, or put more simply, when hell freezes over. Though with the end so tantalisingly close, we might ask why permanent military bases are being constructed by the colonists, and what precisely this has to do with Iraq's supposed independence and our imminent victorious withdrawal.

Accepting that there will still remain a few liberal apologists for the ongoing slaughter, brave contrarians who stubbornly reject the confusing influence of the facts, our role must now be, as those ultimately responsible for the actions of the aggressor governments, to exact the political costs of any continuing failure to withdraw. In doing so we might take our cues, and our inspiration from another movement of another time, but one with some striking similarities to our own.

In April 1967, exactly one year before he was assassinated, Martin Luther King rose at Manhattan's Riverside Church to deliver a blistering attack on the Vietnam war. He said that the US was in Vietnam, not to liberate it, but "to occupy it as an American colony". He roundly condemned his government as "the greatest purveyor of violence in the world today". The Vietnamese, he said, "must see Americans as strange liberators", describing the US record of denying their independence, including support for "of the most vicious modern dictators, our chosen man, Premier Diem...Now they languish under our bombs and consider us, not their fellow Vietnamese, the real enemy....They watch as we poison their water...They wander into the hospitals, with at least 20 casualties from American firepower for each Viet Cong-inflicted injury. So far we may have killed a million of them, mostly children...How can they trust us when now we charge them with violence after the murderous reign of Diem, and charge them with violence while we pour new weapons of death into their land?....Now there is little left to build on, save bitterness. Soon the only solid physical foundations remaining will be found at our military bases...We must speak for them and raise the questions they cannot raise. These too are our brothers".

But then King went further, identifying the war as "but a symptom of a far deeper malady...[part of] pattern of suppression". He warned that "We will be marching and attending rallies without end unless there is a significant and profound change in American life and policy...When machines and computers, profit and property rights are considered more important than people, the giant triplets of racism, materialism, and militarism are incapable of being conquered". Describing "the Western arrogance of feeling that it has everything to teach others and nothing to learn from them", King warned that "a nation that continues year after year to spend more money on military defense than on programs of social uplift is approaching spiritual death".

As a resurgent US anti-war movement marches on Washington, with a parallel march in London, on 24 September, we might recall the efforts, and the victories, of that previous anti-war movement, of which King was a part. Public anger and political pressure played no small part in the US retreat from Indochina. Vietnam went on to become a byword in the political lexicon for military and political disaster. Two years after King's speech, around 70% of Americans had come to see the war, not as "a mistake", but as "fundamentally wrong and immoral". Iraq is not Vietnam. But it is a war of aggression, waged clearly for greed, not liberation, and a bloodbath for which we bear the ultimate responsibility. The political conditions now exist, more so than at any previous point, for us to inflict upon the individuals and the system responsible the most ignominious defeat they have suffered for 30 years.

As King said, "If we do not act we shall surely be dragged down the long, dark and shameful corridors of time reserved for those who possess power without compassion, might without morality, and strength without sight....Shall we say the odds are too great? Shall we [say] the struggle is too hard? Will we send [the victims] our deepest regrets? ...The choice is ours, and though we might prefer it otherwise we must choose in this crucial moment of human history."