When South Sudan became an independent nation in July, there was concern that violence could break out along the new international border that separates the two Sudans.
But an outbreak of violence within South Sudan makes clear that the infant country faces other serious challenges as well.
Authorities say more than 150 people have been killed in the latest violence in South Sudan's vast Jonglei state.
Thousands of fighters from one ethnic group, the Lou Nuer, attacked a town populated by members of a rival tribe, the Murle.
Anchor Marco Werman talks to the BBC's Will Ross, who is in neighboring Kenya, about the inter-ethnic violence in South Sudan.