Last week, the head of the U.N.'s refugee agency declared that the drought affecting around ten million people in the Horn of Africa--particularly those in Somalia, Kenya, Ethiopia, and Djibouti--was the "worst humanitarian disaster" in the world right now. Today, anonymous U.N. sources are telling several news outlets that the organization, after poring over new data from its food security and nutrition analysis unit, will go a step further on Wednesday by declaring a famine in parts of southern Somalia (Somali President Sheik Sharif Sheik Ahmed jumped the gun on Tuesday, stating that there is "in fact a famine" in his country).

While the word "famine" may get tossed around a lot in news reports, the U.N. and other aid organizations don't use the term lightly. As the BBC and The Telegraph explain, the five-stage famine classification system is defined by three characteristics: 1) more than 30 percent of children suffering from acute malnutrition; 2) more than two adults or four children dying of hunger each day for every group of 10,000 people; and 3) the population having access to less than 2,100 kilocalories of food and four liters of water per day (conditions also frequently include dead livestock, displaced persons, and armed conflict). Nicholas Haan, who helped develop the U.N.'s classification system, tells The Telegraph that a famine declaration will put pressure on the international community to step up aid efforts since people's ability to locate food and water has "disintegrated," though a British official adds that there's no legal mechanism "compelling the international community to respond" differently to a famine than to a less serious crisis. Even with the well-defined prerequisites for a famine, however, there appears to be some disagreement over when such a humanitarian catastrophe was last declared. Some aid organizations point to Somalia in 1992, according to the BBC, while The Telegraph mentions Niger in 2005. 

There's a further complication to the crisis in Somalia: The parts of the country that the U.N. believes are suffering from famine are controlled by the Al Qaeda affiliate Al Shabaab, which recently lifted a ban on foreign aid agencies delivering humanitarian supplies. On Tuesday, the U.N.'s refugee agency requested further security guarantees from the militant group in order to provide emergency aid. The U.N. has already begun airlifting food to areas held by Al Shabaab.