Desperate villagers fleeing fighting across the South Sudan are eating grass and roots to survive as the U.N. World Food Program (WFP) begins costly air drops of food to northern parts of the country. But the air drops—three times more expensive than road deliveries—are straining the humanitarian response because only one-third of the $1.27 billion requested by the United Nations has been raised. A large cargo airplane has begun dropping more than 30 tons of food in the northern states. Each drop provides at least 15 days of rations for 18,000 people, intended to help those stranded between pro-government and anti-government soldiers. WFP Director Ertharin Cousin visited Nyal in Unity state on Tuesday before traveling Wednesday to the Ethiopian border town of Gambela, which was overwhelmed by almost 70,000 South Sudanese fleeing the fighting that started in December. Because of upcoming rains, “in a few weeks, this area will be totally inaccessible by road, so in order to continue to feed these people, we need to already have the food in here, and by air is the only means,” Cousin said. Almost 7 million people are at risk of hunger in South Sudan, according to the U.N. Food and Agriculture Organization (FAO). In the 100 days since the South Sudan conflict began, more than 1 million people have fled their homes and 3.7 million now are at high risk of food insecurity.