 Following this defeat , the Islamic Courts Union splintered into several different factions . Some of the more radical elements , including Al @-@ Shabaab , regrouped to continue their insurgency against the TFG and oppose the Ethiopian military 's presence in Somalia . Throughout 2007 and 2008 , Al @-@ Shabaab scored military victories , seizing control of key towns and ports in both central and southern Somalia . At the end of 2008 , the group had captured <unk> but not Mogadishu . By January 2009 , Al @-@ Shabaab and other militias had managed to force the Ethiopian troops to retreat , leaving behind an under @-@ equipped African Union peacekeeping force to assist the Transitional Federal Government 's troops . 
