In this Friday, May 9, 2014 image made from video, South Sudan’s President Salva Kiir, left, and rebel leader Riek Machar, right, shake hands and pray before signing an agreement of the cease-fire of the conflict in South Sudan in Addis Ababa, Ethiopia. The South Sudan’s president has reached a cease-fire agreement with the rebel leader, an African regional bloc said Friday, after a vicious cycle of revenge killings drew international alarm. (AP Video/Associated Press)

South Sudan’s top U.N. aid official on Saturday hailed a new peace deal and called for food aid to flow to counter the risk of mass hunger. A military spokesman said a cease-fire would take hold, but wary skepticism remained, given that this is the conflict’s second peace deal.

The truce signed by President Salva Kiir and former vice president Riek Machar late Friday in neighboring Ethiopia calls for a cessation of hostilities within 24 hours and unhindered humanitarian access.

Although it is the second peace deal of the nearly five-month conflict, the two leaders did not attend talks that led to the first cease-fire in January. This time they stood face to face, a hopeful sign one week after U.S. Secretary of State John Kerry met with Kiir in South Sudan’s capital and spoke to Machar by phone. Days later, U.N. Secretary General Ban Ki-moon flew in, adding to the pressure.

The warfare has thrown an extremely poor country up against the edges of severe hunger. An analysis released Saturday by the World Food Program, Save the Children and the South Sudan government found food needs intensifying to “alarming” levels in areas isolated by conflict, particularly several counties in Unity state.

The fighting, which has often pitted Kiir’s ethnic Dinka against Machar’s ethnic Nuer, has killed thousands of people, often in what a new U.N. report this week said were gross violations of human rights “on a massive scale.” More than 1.3 million people have fled their homes, and aid officials fear that mass hunger will set in later this year.

“Big news from Addis,” Toby Lanzer, the top U.N. aid official in South Sudan said on Twitter on Saturday. “Calling on both parties to facilitate deliveries of emergency relief to people in need now: open roads for truck convoys & rivers for barges.”

John Prendergast, co-founder of the Washington-based Enough Project, which does advocacy work in eastern and central Africa, said, “We will know very quickly whether the parties are serious, as they are right now poised to attack each other in a number of volatile locations on the front lines of the war.”