The United States Agency for International Development (Usaid) administrator, Mark Green has termed South Sudan as the most dangerous country for aid worker and expressed hope that the civil war can be stopped.
Mr Green, in his two-day visit to the South Sudan capital Juba and the northwestern Wau region urged President Salva Kiir to end the suffering of the people by taking a number of specific steps; restoring a permanent ceasefire, ending obstruction of humanitarian access, eradicating exorbitant fees levied on aid organizations and engaging the warring parties in an inclusive peace process.
Currently, there are over 1 million South Sudan refugees in Uganda, who are fleeing the recent flare-up in the southern Equatoria.
With US support, an estimated 1.8 million people in South Sudan receive life-saving humanitarian assistance every month.
President Kiir has been hoping that the National Dialogue he launched in 2016 would help bring peace after four years of fighting, but the war keeps spreading as more ethnic militias emerge.
The United States is the single-largest humanitarian donor to the people of South Sudan, having provided nearly $2.7 billion dollars since the conflict erupted.
South Sudan slipped into civil war in 2013, in a conflict ignited by a feud between President Salva Kiir, an ethnic Dinka, fired his deputy Riek Machar, a Nuer, resulting in around one third of the population -fleeing to neighbouring countries for safety.