Imagine that we could rerun the events that occurred in Rwanda 10 years ago. With the certain knowledge of horrific events to come, would the world's great nations again stand idle as 800,000 human beings faced slaughter? If the recent expressions of grief and regret from world leaders are any indication, the answer is no -- this time things would be very different.

Yet, in 2004, just as in 1994, the international community is on the verge of making a tragic mistake. Mass human destruction is unfolding today in Sudan, with the potential to bring a death toll even higher than that in Rwanda.

Darfur, a Texas-size region in western Sudan, is the site of the worst humanitarian crisis in the world today. Since December the largely Arab Sudanese government has teamed with the Janjaweed, a group of allied Arab militias, to crush an insurgency in Darfur. The methods that the government and the Janjaweed have employed are nothing short of horrific. They are slaughtering civilians in a systematic scorched-earth campaign designed to "ethnically cleanse" the entire region of black Africans. By bombing villages, engaging in widespread rape, looting civilian property, and deliberately destroying homes and water sources, the government and the Janjaweed are succeeding.

The numbers are appalling. Some 1.1 million people have been driven from their homes, and as many as 30,000 are already dead. The U.S. Agency for International Development estimates that, even under "optimal conditions," 320,000 may die by the end of this year, and a death toll far higher is easily within reach. In the face of this catastrophe, the government and the Janjaweed continue to block humanitarian aid, and widespread killing and destruction persist. While civilians flee, the government's Antonov bombers target water wells, granaries, houses and crops, clearing villages so that the Janjaweed can enter and take over. In the meantime, famine looms.

The administration has rightly spoken out against the atrocities in Sudan and taken admirable steps, including the provision of financial support and increased diplomatic pressure. The State Department has also made clear that the Sudanese government is sorely mistaken if it believes it will get a free pass in Darfur in exchange for brokering peace with rebels in the south. But as the rainy season approaches and threatens to hinder the delivery of aid, time is running out. We must do more, and we must do it immediately.

The U.N. Security Council should demand that the Sudanese government immediately stop all violence against civilians, disarm and disband its militias, allow full humanitarian access, and let displaced persons return home. Should the government refuse to reverse course, its leadership should face targeted multilateral sanctions and visa bans. Peacekeeping troops should be deployed to Darfur to protect civilians and expedite the delivery of humanitarian aid, and we should encourage African, European and Arab countries to contribute to these forces.

The United States must stand ready to do what it can to stop the massacres. In addition to pushing the U.N. Security Council to act, we should provide financial and logistical support to countries willing to provide peacekeeping forces. The United States should initiate its own targeted sanctions against the Janjaweed and government leaders, and consider other ways we can increase pressure on the government. We must also continue to tell the world about the murderous activities in which these leaders are engaged, and make clear to all that this behavior is totally unacceptable.

It took concerted international pressure to achieve an end to the 20-year war between the north and south in Sudan, and even greater intensity is required to save lives in Darfur. Some Americans, understandably preoccupied with events in Iraq, Afghanistan and elsewhere, may think that these measures are too difficult or too expensive. Dealing with ethnic strife is never easy, and it is tempting to turn our heads. Yet 10 years ago we looked the other way when Americans were unfamiliar with the Hutu and the Tutsi, and 800,000 deaths now stain our conscience.

A survivor of the Rwandan genocide named Dancilla told her story to a British humanitarian group. She said: "If people forget what happened when the U.N. left us, they will not learn. It might then happen again -- maybe to someone else." All Americans should realize one terrible fact: It is happening again.

Mike DeWine is a Republican senator from Ohio. John McCain is a Republican senator from Arizona.