Tom Stoppard: We must speak up for the dead and dispossessed in an epidemic of rage

If not now, when? If not we, who? News of murder, rape, arson and dispossession in Darfur has been coming in for something like four years, stopping and starting and stuttering, scaling up into horrifying film footage that blanks out the political story, and also down into declarations, resolutions and soundbites that veil the horror of what's really happening in a war so remote and so obscured that the numbers of dead arrive rounded to the nearest hundred thousand.

Is it 200,000 or 300,000?

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Both figures keep popping up in the Darfur story in reproachable documentation and all you can think is that the sub-text "enough is enough" of Tony Blair's reported message to Angela Merkel the other day had an even darker meaning than the phrase was intended to carry.

But, yes, enough is indeed enough. And one of the things you'd think the UN would have had enough of is being treated with casual disdain by the Sudanese regime, whose latest gesture was to use troops to deny the UN's humanitarian delegation access to a refugee camp in the Darfur region.

A peacekeeping mission would be more to the point, and here again the UN is as helpless against its own vetoes as against President Omar al-Bashir's soldiers.

If the United Nations could die of shame it would have been dead years ago.

How can the EU do better? Can it be effective at all? Yesterday, the British Prime Minister and the German Chancellor were making the right noises. Stringent sanctions. No-fly zones.

But the unpalatable truth is that sanctions require a degree of collective determination, of which the UN appears constitutionally incapable. A no-fly zone over that vast remote area represents an enormous challenge. And would freezing Sudanese assets abroad, one of the suggestions in the "writers' letter", in itself turn the situation around?

Bob Geldof, who orchestrated the letter, said yesterday: "It's code to get the UN behind us."

Well, maybe. But the point about Geldof is that he is a populist. What is needed is to make rage and shame contagious, an epidemic. The situation will be turned by numbers, vast numbers of the living outraged, to speak up for the 200,000, or was it 300,000, dead.