This February memo to local Sudanese forces, translated from the Arabic, is part of a cache of documents that make clear the role of the Khartoum government in Darfur's charred villages, raped women, and starving children. Despite denials from the government, these documents, marked "highly confidential," reveal that Sudan in fact directs what the United Nations has called a "campaign of terror" in western Sudan. The main agents of Darfur's nightmare are known as the Janjaweed militia: mounted marauders from Arab nomadic groups who target civilians from the Fur, Zaghawa, Massalit and other black African ethnic groups. As mass famine looms, the killing and rapes led by Sheik Musa Hilal and other militia leaders continues.

Just as meticulous records were kept of the attacks on civilians in Saddam Hussein's Iraq and Slobodan Milosevic's Kosovo, so it appears Sudanese record-keepers have incriminated themselves. Human Rights Watch has obtained this damning new evidence—in the Sudan government's own words—that Khartoum is responsible for ethnic cleansing. While Sudan continues to fend off international action or censure by claiming ignorance or impotence, these incriminating government records make plain as day Sudan's role in creating, arming and directing these bloody militias.

In February, at the same time as Sudan's president, Omar Hassan Ahmed al-Bashir, pledged publicly to "end all military operations in Darfur," his underlings were ordering regional officials to increase recruitment and support for "loyalist tribes."

In a series of official Arabic-language memos dating between November 2003, and March 2004, from government authorities in North and South Darfur, senior Sudanese government officials call for recruitment and military support to the nomadic groups who make up the Janjaweed militia. One memo called on local officials to deliver "provisions and ammunition" to known Janjaweed militia leaders and camps. "Prepare for the recruitment of three hundred knights," says another, referring to additional Janjaweed. Other memos such as the one excerpted above pass on orders from the Ministry of the Interior to governors and mayors.

A more recent letter indicates Sudan could implement a sinister plan to resettle Arab nomads into the areas from which a million black Africans were driven into government-run refugee camps, many in neighboring Chad. One especially grisly facet of the government's campaign in Darfur has been the destruction—often by poisoning with the bodies of murdered villagers—of wells in water-starved Darfur. The same memo proposing resettlement of nomads recommends rehabilitation of wells and water resources in the areas of resettlement. Meanwhile, the government proposes to "resettle" the million or so displaced people in 18 new locations, a plan that would make permanent the ethnic cleansing that has taken place.

These documents expose the Big Lie—or more accurately a series of Big Lies. At first, top Sudanese government officials simply denied that the Janjaweed militia existed. Once this tactic fell in the face of the testimony of hundreds of victims and witnesses, Khartoum acknowledged the existence of militias but refused to admit the government's responsibility for arming them. The killing and massive civilian displacement may have been occurring on Sudanese territory, but the government claimed it knew nothing about it. Absurd, of course, but the world community has stood by while being fed bald falsehoods.

Then, for the past several months, the Sudanese government found new ways to play the U.N. and America for fools. In April, Khartoum pledged to "neutralize" militias, even as it continued recruiting and arming militias to fight in new areas of Darfur. In response to evidence that the Janjaweed were backed by government air cover and wear Sudan government uniforms, Khartoum then swore it would "rein in" the killers.

The U.N. and America decided to support African efforts to cope with the catastrophe. Unfortunately, the African Union initiative has so far been able to muster only 80—that's right, 80—ceasefire monitors on the ground in Darfur, a part of Sudan the size of California.

Not even visits this month by U.N. Secretary-General Kofi Annan and Secretary of State Powell made much difference on the ground. Mr. Annan and his staff were visibly horrified when the 1,000-person internally displaced camp they had arranged to inspect was abruptly "disappeared." Al Noor Muhammad Ibrahim, minister of social affairs for the state of North Darfur, explained that the camp was moved because "We did not like seeing people living like that."

Conditions in the camps are appalling, and thousands of people risk dying from disease and famine each week that passes without serious progress. But even such a publicly embarrassing bait and switch has not convinced the U.N. of the need to move quickly.

When asked on Monday whether the U.N. Security Council should adopt a resolution on Darfur, Mr. Annan said, "The important thing is the international community should make clear that they do expect the Sudanese government to honor the commitments it made."

In the case of earlier ethnic cleansings, the world shrugged in the absence of a smoking gun that a repressive regime played a key role in directing mass killing. These memos amount to a series of smoking guns and demand immediate action to punish Sudan.

The international community has been too late to stop phase one of Sudan's deadly campaign against Darfur's people—the violent displacement—but could still do something about the next phases: the deaths of thousands from famine and disease and the consolidation of ethnic cleansing.

The U.N. Security Council has a last chance at redemption this week when an American drafted resolution sanctioning Sudan is considered. An arms embargo and travel bans for top Sudanese officials would tell Sudan's leaders that the international community is well aware of their responsibility for Darfur's tragedy. Even better would be an international civilian protection force not answerable to the government of Sudan and an international commission of inquiry into abuses. The paper trail establishing official complicity shows why ending the killing can't be left to Khartoum.