Barack Obama spoke often and passionately about Darfur while campaigning. But the African holocaust that will confront him first is the ongoing slaughter in the Democratic Republic of the Congo. More than 5 million have died in that conflict since 1996, and there's no sign of a letup. As rebels commanded by Laurent Nkunda, a renegade Congolese Army general, closed in on the city of Goma in recent weeks, the United Nations' 17,000 troops-- its largest peacekeeping force in the world--proved too weak to stop the push or to prevent a rampage of rape and looting by government forces who were there to defend the city. The U.N. Security Council voted unanimously last week to send in 3,100 more troops, but "you would need a minimum of 100,000 soldiers to have a credible peacekeeping force in Congo," says Knox Chitiyo, an Africa expert at the Royal United Services Institute, a London think tank. Chitiyo thinks only an envoy of Obama's stature might be able to impose a settlement.