After four years of civil war marked by brutal attacks on civilians, the United States is reviewing its support for South Sudan, USAID administrator Mark Green told the country's President Salva Kiir in talks in the capital Juba. WAU, South Sudan: After four years of civil war marked by brutal attacks on civilians, the United States is reviewing its support for South Sudan, USAID administrator Mark Green told the country's President Salva Kiir in talks in the capital Juba.