The United Nations has described the situation in Darfur as the world's gravest humanitarian crisis. In 2004, then-secretary of state Colin Powell called it genocide. On Tuesday, a US Congressional delegation that had visited Sudan told UN Secretary-General Kofi Annan, "The issue of Darfur challenges the conscience of our country." So what is being done about it? Darfur is a province in the southwest of Sudan, an Arab country. The area had a population of about 6 million - about 2 million have fled to neighboring Chad, while about 400,000 were killed by the Sudanese military and the Janjaweed militias...