Impact and needs assessment involves assessing the nature and magnitude of a disaster, its impact on affected populations and on agriculture, livestock, fisheries and forestry, and the type and extent of emergency and immediate rehabilitation assistance that is required. FAO mounts missions to carry out such assessments which aim to determine the needs for both food assistance and for emergency assistance in agriculture. For the former, missions are mounted by FAO's Global Information and Early Warning System on Food and Agriculture (GIEWS) in conjunction with the World Food Programme (WFP). These missions are responsible for identifying vulnerable groups and for food aid needs assessment. The impacts of disasters and emergency assistance requirements for the agriculture sector are assessed by specialists fielded through FAO's Special Relief Operations Service (TCOR)