The crisis in South Sudan has been in a downward spiral for months, and now the United Nations says hundreds of civilians were rounded up and killed by a rebel group when it recently took control in the town of Bentiu, an oil hub.
The White House condemned the attacks as an "abomination" and implored the country's leaders to end the cycle of violence.
The U.S. was deeply involved in helping South Sudan's establish independence from Sudan in 2011, which raises the question of what the U.S. is willing to do as the fledgling nation faces the growing possibility of a full-scale civil war.
And why have things gone so badly wrong in South Sudan?
When I arrived in the capital Juba at the end of last year, a shootout in a military barracks had sparked violent conflict around the country, pitting loyalists of President Salva Kiir against those allied with his political archrival, the former vice president, Riek Machar.
Parallels
How I Almost Got Arrested With A South Sudanese Ex-Minister