The world’s leading statesmen regularly affirm their commitment to preventing crimes against humanity, but that doesn’t stop genocide and ethnic cleansing from unfolding in plain sight. Empty promises of “never again” were not enough to prevent the Rwandan and Bosnian tragedies. Ethnic cleansing is reappearing, this time in western Sudan, again to silence.

Sudan is no stranger to internal conflict. The largely Christian south has fought the country’s Islamic government in the north for more than 20 years in a civil war that has claimed 2 million lives. That conflict widened last year when two rebel groups from the western region of Darfur joined the fray. The result has all the horror of past crimes against humanity. The government in Khartoum, Sudan is supporting local Arab militias in a systematic campaign aimed at cleansing the Darfur region of its black population.

International aid workers corroborate eyewitness accounts of the people of Darfur. Militias traveling on horseback, armed with guns and grenades and often accompanied by helicopter gunships, are looting and burning black villages. The campaign of ethnic cleansing has left nearly 30,000 dead, 1 million displaced from their homes and 110,000 refugees huddled in neighboring Chad. The Sudanese government denies arming the militias, even as it works to exclude humanitarian and relief officials from the region.

The government in Khartoum is undoubtedly encouraged by the lack of outrage around the world. Few Western reporters have visited the Darfur region. Those who have often portray the violence as tribal conflict rather than ethnic cleansing. U.N. Secretary-General Kofi Annan, mindful of Rwanda’s experience, said the international community should consider military intervention to halt the violence. His comments, and other human rights advocates’, should not end up on the cutting room floor.

A U.N. human rights mission concluded a three-day visit to the Darfur region Wednesday with a draft report alleging the actions of the government-backed militias could be crimes against humanity. The U.N. Security Council should follow that work with a resolution authorizing military intervention in western Sudan. Anything less is an affront to the promise “never again.”