A drastic reduction in humanitarian assistance, widespread conflict and drought combined to make the 2011 famine in Somalia the most deadly in the past 25 years, a May 2013 study finds. Commissioned by the United Nations’ Food and Agriculture Organization (FAO) and the United States Agency for International Development’s (USAID) Famine Early Warning Systems Network (FEWSnet), the study estimates that between October 2010 and April 2012, nearly five percent of the region's population and 10 percent of its children died because of severe food shortages. It also noted “that limited access to most of the affected population, resulting from widespread insecurity and operating restrictions imposed by several relief agencies, was a major constraint.” [p. 5] The presence of al-Shabab, a group on the U.S. terrorist list, in famine affected areas made legal restrictions an issue for aid groups.