The Somali Islamist militant group al Shabab has claimed responsibility for the attack on a shopping mall in Kenya's capital, showing it can still strike back despite coming under pressure in Somalia from offensives by African troops, including Kenyans.
Here is a look at a timeline of al Shabab attacks in Somalia and other countries:
* The toppling by warlords of military dictator Mohamed Siad Barre in 1991 plunged the Horn of Africa nation into anarchy, allowing al Shabab, which means "Youth" or "Boys" in Arabic, to seize control of large areas of south and central Somalia.
* Al Shabab's militia was part of Somalia's Islamic Courts Union movement that pushed US-backed warlords out of the capital Mogadishu in June 2006 and ruled for six months before Somali and Ethiopian forces ousted the movement.
* Five years on, in August 2011, al Shabab began pulling its fighters out of Mogadishu. In September 2012, African peacekeepers pushed the group out of the port of Kismayu.
* Although the rebels have still struck back repeatedly with bombs and attacks, their retreat from Mogadishu and Kismayu signalled they could not defeat militarily a government backed by foreign firepower. Ethiopian, Kenyan and African peacekeeping (AMISOM) troops have advanced and taken rebel strongholds.
* Al Qaeda said in early 2012 that al Shabab had joined its ranks and the group has resorted to guerrilla-style hit-and-run attacks against AMISOM troops. At least 3,000 African peacekeepers have been killed in Somalia since 2007, the United Nations says.
* A suicide bomber killed four government ministers and 19 others on December 3, 2009 at a graduation ceremony for medical students in Mogadishu.
* In July 2010, al Shabab staged a bomb attack in Kampala that killed 79 people who were watching the soccer World Cup final. The strike, its first on foreign soil, was to avenge Uganda's participation in the African peacekeeping force.
* Two attacks on a Nairobi bus station and a bar killed one person and wounded more than 20 in late October 2011.
* Kenya blamed al Shabab for grenade attacks that killed at least six people at a Nairobi bus station on March 10, 2012.
* Somali sports officials were among six people killed in April 2012 in an al Shabab suicide bombing in Mogadishu.
* Suicide bombers hit the Mogadishu hotel where newly elected President Hassan Sheikh Mohamud was on Sept 12, 2012, killing eight people. Mohamud was unhurt. Eight days later, suicide bombers killed at least 15 people in a restaurant.
* In April 2013, al Shabab militants killed at least 30 people in a wave of coordinated attacks in the Somali capital.
* In July, the group claimed a car bomb attack on the Turkish mission in Mogadishu that killed three people. A Sept 7 attack on a packed restaurant killed at least 15 people.