The United States on Friday named a special envoy to seek progress in the crisis in South Sudan, whose rival leaders have repeatedly missed deadlines to end their devastating conflict. The State Department said that Stuart Symington, a retired ambassador with long experience in Africa, "will lead US efforts to support the peace process and a successful political transition in South Sudan."

The United States has been a major supporter of the impoverished, majority-Christian nation that won independence from Sudan in 2011, contributing around $1 billion a year in food and other humanitarian aid.