There's still debate over who shot down the plane carrying the Hutu President of Rwanda in 1994, but there's no doubt what happened next: the systematic slaughter of up to a million rival Tutsis — men, women and children — in roughly 100 days. Instead of intervening, the UN Security Council withdrew all but 200 peacekeepers as the slaughter went on. Former President Bill Clinton has apologized for America's failure to act. This week has been one of commemoration, in a country that has reconstructed itself so completely it's even a good place to do business. Once again, Hutus and Tutsis live side by side — after almost two million so-called "trials of reconciliation" -- but some still insist that justice has not been served. What are the lessons for neighboring countries where ethnic hatred is the cause of widespread violence and for the international community?