U.N. Secretary General Ban Ki-moon has told South Sudan's leaders that respecting the terms of a peace agreement is not an option. The leaders of the young African state are attempting to form a government of national unity as the country emerges from civil war.

Ban said Thursday that the government of South Sudan must step up to its responsibilities and protect the population, which has suffered violence, mass displacements and hunger. He asked the leaders to put peace above politics and establish a transitional government of national unity.

South Sudan was plunged into civil war two years ago after a falling out between President Salva Kiir and his deputy, Riek Machar sparked a political crisis that then boiled over into a violent rebellion.