THE EARLY PREPARATION for the genocide in Darfur, Sudan's vast western province, played out behind a veil of ignorance: Almost no foreign aid workers operated in the region, and the world failed to realize what was happening. Stage two of the genocide, the one we are now in, is more acutely shameful: A succession of reports from relief agencies, human rights groups and journalists informs us that hundreds of thousands of people are likely to perish, yet outsiders still cannot muster the will to save them. Unless that changes, we are fated to live through the genocide's third stage. There will be speeches, commissions of inquiry and sundry retrospectives, just as there were after Cambodia and Rwanda. Never again, we will be told.

It is already too late to prevent death on a scale that taxes the imagination. Sudan's murderous government and its allies in the death squads known as the Janjaweed have killed an estimated 30,000 people in Darfur since a rebellion broke out there a bit over a year ago. The crackdown has chased more than 1 million people from their homes and villages. Refugees crowd into camps that the Janjaweed encircle, as food supplies dwindle and their children die for lack of clean water and medicines. The rainy season, now beginning, will make it hard to deliver relief supplies, and starvation seems probable. On Thursday, Andrew Natsios, administrator of the U.S. Agency for International Development, declared that in an optimistic scenario -- meaning one in which significant relief is delivered -- some 300,000 people might perish. That is the equivalent of Sept. 11, 2001, 100 times over. The worst-case scenario, according to Mr. Natsios, is a death toll that approaches 1 million.

Sudan's government is delighted with this slaughter. It perfected the art of ethnic cleansing in its long war against the country's southern rebels, and it has expertly repeated the process in Darfur. The formula is to destroy villages using a combination of informal militias and government air power, then to deny relief organizations access and let starvation do the rest. When international protests heat up toward the boiling point, some humanitarian access is granted, but it's always late and inadequate.

So it is now in Darfur. The United States recently landed nine planeloads of relief supplies, and the government has relaxed visa restrictions that had kept aid workers out. But the Sudanese regime still demands that relief supplies be transported on Sudanese trucks and distributed by Sudanese agencies, and that medicines not manufactured in Sudan undergo time-consuming testing. The only plausible explanation: Sudan's government wants people to die by the tens of thousands. Meanwhile, Darfur's rebels do not make things easier. Sketchy reports over the weekend indicated that the rebels took 16 aid workers hostage before releasing them Sunday.

The United States, Britain and Norway have been anxious to broker and implement a north-south peace and so have shrunk from pressuring the northern government for greater access to Darfur. Outsiders pretend to believe that a team of 60 or 100 observers from the African Union will be enough to end the atrocities in Darfur, a region the size of France, and they pretend to hope that Sudan will grant full humanitarian access without being bullied into doing so.

The tragedy is that aggressive diplomatic pressure would have a good chance of working. In the past, Sudan's government has been pushed into expelling Osama bin Laden, negotiating with the southern rebels and signing a paper cease-fire in Darfur. The United States and its allies should press for a U.N. Security Council resolution demanding full and immediate humanitarian access. They should encourage Kofi Annan, the U.N. secretary general, to force the world's attention onto the crisis; a letter by Rep. Frank R. Wolf (R-Va.) calling upon Mr. Annan to visit Darfur has attracted 45 signatures in Congress. And they should authorize the use of military escorts for emergency aid. The United States is overcommitted militarily in Iraq and elsewhere. But this is a mission for which European countries ought to make troops available.