NAIROBI, Kenya (AP) — The government of South Sudan and rebel opposition groups on Thursday signed a “commitment declaration” for peace during high-level mediation talks in Kenya, described as key step in efforts to end the conflict in South Sudan that has long crippled its economy.

The content of the agreement was not made public during the signing ceremony, attended by diplomats and civil society groups.

The rebel opposition groups were not part of the 2018 agreement that ended South Sudan's five-year civil war that left 400,000 people dead and millions displaced.

Kenya’s foreign office said the agreement was a “first milestone” in the ongoing talks in which warring sides pledged their commitment to end the violence and hostilities.

At the start of the high-level mediation talks launched a week ago, South Sudan’s President Salva Kiir thanked his Kenyan counterpart, William Ruto, for hosting the negotiations.

The talks have been dubbed Tumaini, Swahili for hope, Initiative and are led by former Kenyan army commander Lazarus Sumbeiywo.

South Sudan is due to hold elections in December but remains politically fragile, in part because the 2018 peace agreement is yet to be fully implemented and because conflict and violence continues in different parts of the country over ethnic and political differences.