The agreement, reached between President Salva Kiir and his former Vice-President Riek Machar, is the latest hope to end a bitter conflict plaguing South Sudan – the world’s youngest nation – for much of its short existence.

Over 50,000 people have been killed and millions displaced from their homes in almost five years of bloody fighting.

It is beholden on all of us here today to help encourage trust between parties – David Shearer, head of UNMISS

According to David Shearer, the Special Representative of the Secretary-General for South Sudan and the head of the UN Mission there, the greatest challenges are yet to come during the implementation phase.

“The key ingredient still lacking is trust. The personalities signing the agreement have in the past been former friends and foes. From my discussions with all parties, suspicion is widespread… These people have got animosities that go back two decades, three decades even.”

Resolving those differences is vital for a better future of the country, he said, underscoring that it is “beholden on all of us here today to help encourage trust between parties.”

UN Secretary-General António Guterres also highlighted the challeges ahead and called on the international community to “remain seized” of the situation in South Sudan throughout the implementation of the peace agreement.

In a statement from his spokesperson, the UN chief said that the Organization stands ready, in close coordination with the Inter-Governmental Authority on Development (IGAD, an eight-country trade bloc in Africa) and the African Union (AU), to assist the parties in implementing the agreement.

The peace agreement – signed on Wednesday at the main UN office in the Ethiopian capital Addis Ababa – follows 15 months of negotiations led by the IGAD and the Governments of Sudan and Ethiopia.

The regional leadership was crucial in bringing the parties together, highlighted Mr. Shearer, noting the role the UN and the international community will be expected to play in assisting with genuine reconciliation and peacebuilding activities.

“However, we need to be persuaded by the demonstration of collective political will of the parties to implement an agreed and realistic implementation plan,” he stressed.

The new agreement comes in the aftermath of a series of failed peace deals, including a similar one between the two political rivals in 2015. Under the new agreement, Mr. Machar – who has lived in exile since 2013 – will return to South Sudan and be reinstated as Vice-President under a power-sharing arrangement.