A humanitarian disaster is unfolding right now in the Darfur region of Sudan, and it could be prevented. More than 300,000 people, most of them ethnically African, have been killed in the past two years. Some 3.3 million have been forced to flee into camps as a campaign of terror by Janjaweed militias and the army of the government of Sudan clears large areas of the region. The campaign is co-ordinated and systematic. NGOs that hope to give limited help are themselves subject to intimidation. The latest reports suggest that up to 40 per cent of those designated ethnically African cannot be protected.

Rebels fighting the government have also attacked camps and killed civilians. There is, however, an utter disparity in power and violence perpetrated, between the rebel groups and the government/Janjaweed forces. Moreover, the government deploys an overtly Arab-supremacist ideology, chillingly expressed in Janjaweed chants of "Kill the blacks, kill the slaves", and evidence exists of written orders from the government "to change the demography of Darfur and empty it of African tribes".

An important element of this campaign of intimidation, depopulation and murder has been the use of sexual violence. Last month, Amnesty International reported on a "dramatic increase in the numbers of rapes" in Darfur. Amnesty, Unicef, the Aegis Trust and other groups that take a range of views on the conflict all agree that sexual violence is central and systemic to this conflict.

There are few cases of straightforward genocide in which a dominant state sets out to annihilate an ethnic group because of who they are (rather than what they do or think). The Nazis arguably did so against the Jews; Rwanda's Hutu génocidaires did so against the Tutsis. But there are many more cases in which mass killing escalates out of intra-state conflicts that spill over into other states. There are two things that set these kinds of cases apart from "ordinary" civil wars. The first is the killing of significant numbers of civilians because of identities projected on to them. The second is that these projected identities determine who lives and who dies. The killing becomes the purpose of the project: civilians are killed not for a piece of land or other resources, but because of who they are. This kind of killing creates a cycle in which victims then kill for reasons equally meaningless strategically or economically. Such repri sals lead people to question the use of the word genocide.

As in Rwanda, there has been an unconstructive debate about the appropriateness of the term in Darfur. We seem to be frightened of seeing genocide as something distinctive; the debate becomes a word game - is this conflict genocide or is it not? Rather than becoming trapped in semantics, however, we ought to focus on how state-sponsored mass murder acquires a dynamic of its own.

Darfur, and Sudan more generally, was for 200 years a victim of both Egyptian and British imperialism. Then, for generations, the region was neglected by the central government of Sudan. The Sudan Political Service, which governed the area during colonial rule by the British, treated Darfur as a little piece of "authentic" Africa in which it could play king. This institutional condescension created a template of indifference with which post-independence governments in Darfur have continued to operate. In the hands of the post-colonial ruling elite, this template was given an Arab-supremacist inflection that then became an ideology of mass murder. The 1984-85 famine showed the world the extent of central government indifference to the fate of Darfur.

During Sudan's long civil war, the Darfur region was further isolated. When the Comprehensive Peace Agreement was signed in January 2005, a quick Darfur Peace Agreement was also put in place, but it did nothing to meet the needs and demands of the people of Darfur.

How can the "international community" respond to crimes against humanity that are products of post-colonial politics and ideologies but also rooted in imperial legacies? First, we should admit that we are not an international community but a set of competing interest groups. In a unipolar world governed by the United States, it has been in the interests of some groups to pretend that intervention to prevent crimes against humanity or genocide is impossible.

But this is simply not true: China and other states have protected the Khartoum government while the US has been powerless to act. The reality is that Washington could do nothing to stop any state acting unilaterally to stop this kill ing, and would actually welcome anyone doing so.

Mesmerised by US history and by post-invasion Iraq, the international human-rights industry has also been slow to state what is now obvious. This is not an American problem. This is not a British problem. This is not even an EU problem. None of them could take the lead in solving it. This is an African, Arab and Asian problem. The solution is not invasion, or occupation, or regime change. The solution is in the hands of China and the African, Arab and other Asian states that surround, trade with and finance Sudan.

No-fly zone

What could these states or groups of states do? Khartoum has been persuaded to accept the deployment of a limited hybrid force. The first part of a UN force, comprising 43 military staff officers and 24 policemen, arrived in Sudan on 28 December: this deployment must now be built upon in various ways. First, the initial deployment of UN troops in Darfur should be hugely speeded up and extended. Second, a UN resolution should authorise the imposition of a no-fly zone over western Darfur to protect the camps of internally displaced people.

The government in Khartoum should accept both of these actions by acknowledging that it is no longer in control of the situation and that it requires help to protect aid supplies. But it should be made clear that both interventions will be non-consensual if necessary. President Omar el-Bashir's government has taken a series of gambles on the indifference of the world to the fate of Darfur's people, and he will continue to do so. At the same time he cannily presents Sudan as an Islamic state that is the victim of imperialist intervention in search of oil. It isn't, and the imperial power chasing oil hardest in Sudan at this moment is communist China.

There is a simple enough response to this charade. The deployment should be made up from Asian, African and Arab states and the regional organisations representing these states should make it clear that the government of Sudan will be completely isolated unless it moves to control the Janjaweed. Equal pressure must be put on states and groups currently supporting the rebels, especially Chad. The role of the west and nations that trade with Sudan - for example, Japan, China and Malaysia - is to bring economic pressure to bear on the Sudanese government and to offer economic incentives.

It is clear what needs to be done to bring peace to Darfur. But will it happen? A humanitarian disaster is unfolding before our eyes and cannot be prevented. A hybrid force may gradually be deployed over the next eight or nine months, by which time many thousands will have died and the government and rebels alike will have become radicalised by each other's actions. The fighting will continue to spill into neighbouring states. The civil war in Sudan between north and south may start again. But the long-term consequences of Darfur will go far beyond these terrible possibilities. They will be profound for the system of international relations in the post-Iraq-war world and they will seriously challenge European ideas of the universalism of human rights. This universalism holds that there are some things that all human beings should enjoy and some things no human being should endure.

Western imperialism can be blamed for many things, but there is no imperialist explanation for why African, Asian and Arab states do not act over Darfur. They face no logistical obstacle to establishing a no-fly zone. The problem is one of will, not agency or capability.

What ought to unite us against genocide is that, in the end, there is no conceivable geopolitical gain to be had from working with genocidal regimes. The path they have embarked upon has no strategic dimension and it will, in time, self-destruct. These are allies you do not wish to have, neighbours you cannot trust, crimes you cannot live with.

Brian Brivati teaches genocide studies at Kingston University. Additional research by Philip Spencer