The protracted crisis that has gripped Somalia since the collapse of the Siad Barre regime in 1991 has to date produced a total of some Somali 542,000 refugees in the four main asylum countries in the region - Djibouti, Ethiopia, Kenya and Yemen - and some 1,550,000 internally displaced persons (IDPs). With the escalation of fighting since May 2009 between the Transitional Federal Government (TFG) and insurgent forces, both forms of displacement have soared dramatically.

In Kenya, which has borne the brunt of the external displacement, UNHCR has registered an average of 7,000 newly arriving Somalis each month, mostly in the border camps of Dadaab, for a cumulative total of some 310,000 by the end of 2009. In Ethiopia, the total Somali refugee population stood at 59,000; in Djibouti at 11,200 and, across the Gulf of Aden in Yemen, at more than 161,000.

In all four countries, UNHCR and its partners were already struggling to respond fully and effectively to the protection and assistance needs of these refugees. The camps, particularly in Dadaab, have become heavily congested and, for the most part, international standards for water, shelter, health care and sanitation were barely being met.

When, early in 2010, the fighting intensified yet further and the World Food Programme (WFP) was forced to suspend a major part of its emergency food distribution in south and central Somalia, UNHCR decided to review its emergency response preparedness for the Somali humanitarian situation as a whole, that is, in Somalia itself and the four main countries of asylum, all party to the 1951 Refugee Convention.

The Office reviewed the way in which displacement in or from Somalia could evolve throughout 2010, and established planning figures accordingly for a humanitarian response. Furthermore, in close cooperation with WFP and other partners, UNHCR developed a contingency plan to respond to the prospect of a new displacement emergency. Two key scenarios formed the basis of the plan, the "Most Likely Scenario" and the "Worst Case Scenario".

The Most Likely Scenario foresaw that a situation of protracted fighting would continue throughout 2010 in southcentral Somalia between the TFG and its insurgent opponents with no clear outcome, leading to steady displacement of civilian populations away from combat zones. It was projected that, in this scenario, a total of 315,000 Somalis would be newly displaced by the end of the year, 120,000 of them internally and some 195,000 externally into Kenya (100,000), Ethiopia (50,000), Yemen (40,000) and Djibouti (5,000). In the Worst Case Scenario, there would be an acute escalation in the fighting between the TFG and its opponents, possibly involving foreign intervention and triggering sudden and large population movements both inside Somalia and across its borders over a period of 3 to 4 weeks. It was estimated that, in this short period of time, some 500,000 Somalis would be displaced from their homes, 160,000 of them internally and 340,000 externally, 200,000 to Kenya, 100,000 to Ethiopia, 30,000 to Djibouti and 10,000 across the Gulf of Aden into Yemen.