We have a responsibility to protect the people of Burma. But how?

This weekend, unless Burma's generals rediscover in their shrivelled souls some remnant of human decency, there will take place in the Irrawaddy delta one of the most grotesque events in the political history of the modern world. While dead children still lie face-down in muddy flood waters after a devastating cyclone, while survivors become sick with life-threatening diarrhoea, while international aid workers are prevented by the military regime from bringing in supplies that could save them, Burmese citizens will be herded into makeshift polling stations to approve by plebiscite a constitution that is designed to prevent the results of a democratic election held 18 years ago ever being respected. The results of the referendum will be falsified, of course, as they already have been in other parts of the country, where 93% of voters were said to have been in favour, on a turnout of more than 99%. Down in the Irrawaddy delta, you can be sure the dead will vote early and vote often.

This from a junta that last year brutally crushed mass protests - led by Buddhist monks in their crimson and saffron robes - which were much more purely non-violent than those in nearby Tibet. This from a regime which, over decades, has reduced what was historically one of the more prosperous places in southeast Asia to one of the poorest and most oppressed. If ever a country needed regime change, it is Burma.

So what should we do about it? The French foreign minister, Bernard Kouchner, has led the debate on this, invoking the notion of an international "responsibility to protect" (R2P) which was cautiously blessed by the United Nations in 2005. Although it was mainly intended for other purposes (for instance, stopping genocide and ethnic cleansing, as in Rwanda and Bosnia) R2P is a useful way in which to think about what we can do for Burma, starting with the fact that the R stands for responsibility (to protect), not right (to invade).

The Canadian-backed international commission that produced the seminal report on R2P in 2001 deliberately made this shift in emphasis. When is that responsibility triggered, and what is the threshold that justifies intervention, up to and including the use of force? The commission updated some time-honoured thinking about "just war" to identify six criteria: just cause, right intention, last resort, proportional means, reasonable prospects and right authority. Among the conditions that would give just cause for intervention it listed "overwhelming natural or environmental catastrophes, where the state concerned is either unwilling or unable to cope, or call for assistance, and significant loss of life is occurring or threatened". Well, here we are.

I have no doubt that we have a responsibility to act in this case, and that we have just cause to do so without the explicit consent of Burma's illegitimate rulers, who are letting their people die rather than letting in international aid. Unlike over Iraq, I would credit even George W Bush with right intention here. I suppose you could Noam-Chomskyishly argue that the interests of the west might be served by gaining influence over a buffer state between India and China (and, yes, Burma does have oil), but I don't think that's why a US ship is standing off the delta with helicopters and supplies. Proportional means? Yes, air drops and a "sea bridge" for aid would seem proportionate to save the lives of certainly tens of thousands, and potentially hundreds of thousands, of men, women and children.

With the other three principles, things get more complicated. Right authority should mean, ideally, a UN security council resolution. Kouchner rapidly discovered that we won't get this. That leaves something like the legitimation of the Kosovo intervention, pithily described as "illegal but legitimate". But whereas action over Kosovo was supported by a majority of its neighbours and of the world's democracies, this one would not be (starting with the world's largest democracy, neighbouring India).

Last resort means you've tried all other ways. That's tough in this case, because while you are trying, people are dying. But can we really say we've exhausted all other possibilities? The fact is, thanks to visits like those of the UN secretary general Ban Ki-moon and British Foreign Office minister Mark Malloch Brown, and thanks to some (although not enough) pressure from China and other Asian neighbours, the regime has now agreed to let in more aid under the flag of Asean. There are charities working on the ground in the delta, including British outfits such as Save the Children and Merlin, using local employees. If we keep our elbow to the door, are ingenious as well as persistent, and work closely with China, India and Thailand, it seems we may be able to get more of the western, rich countries' aid in under - so to speak - an Asian umbrella. Perhaps a "sea bridge" could even be built using Indian ships, or simply boats flying an Asian flag of convenience, to transport the supplies from the waiting British, American and French ships. Too little, too late, but what's the alternative?

Asking that question brings us to one of the most important criteria: reasonable prospects - of success, that is. Consider the likely consequences of military-protected unilateral air drops and "sea bridges" from those American, British and French ships. I am told that these would have little chance of getting what is really needed - now mainly sanitation, clean water, medical supplies and care, as well as food and shelter - to those who mainly need it, often in remote, cut-off settlements. For that, you need light local transport and trained medical and aid workers on the spot.

Some observers scoff: "You don't seriously think the regime's pitiful forces would try to stop it?" Well, I do, because they already have. As of last weekend, they had only allowed three - three! - foreign aid workers into the delta. NGOs locally express the fear that such an action would lead to an immediate suspension of other aid supplies. The generals' indifference to the fate of their own people is matched only by their selfishness, cynicism and loss of contact with reality. Could they be so stupid? They could be so stupid.

The responsibility to protect has to be exercised responsibly: that is, with a careful, informed calculation of the likely consequences. I conclude that we should use every means except that of military-backed unilateral - or western "coalition of the willing" - action, which has few reasonable prospects, is arguably not the last resort, and would not have right authority. This does not mean we do nothing. We have a responsibility to act by every other means available, and there are many forms of "intervention' short of the military. (For us ordinary citizens, that includes ensuring the charities that do operate there have sufficient funds. In Britain, one good way to do that is through the multi-charity Disasters Emergency Committee, dec.org.uk.)

As for those criminal generals, who, believe it or not, consider themselves to be good Buddhists, I will say only this: they have already produced so much bad karma that, if there is any justice in the great cycle of things, they will all come back as rats.

Timothy Garton Ash