Summary An attack over the weekend by Somali militant group al Shabaab on an upscale shopping mall in Nairobi, Kenya, is the largest such act attributed to the group in more than three years and is likely the result of shifting intentions on the part of its leadership after a tumultuous period of infighting. The attack on the Westgate Mall --- which began around noon on Sept. 21 and has reportedly left more than 70 people dead -- will likely trigger retaliatory strikes by Kenyan security forces inside al Shabaab strongholds in neighboring Somalia as well as riots or reprisals against Somalis living in the Eastleigh district of Nairobi. More than 48 hours from the start of the attack, several gunmen remain barricaded in the mall, and Kenyan security forces backed by foreign advisers are attempting to bring the situation under control. Al Shabaab has not successfully carried out an attack of this magnitude since 2010, when suicide bombers sent by the group killed 74 people in Kampala,