The deadly terror attack at Nairobi's Westgate Mall has taken dozens of lives and brought one of Africa's most-prosperous cities to its knees. It has also highlighted a disturbing new reality: the Islamist extremism that has long ravaged the Middle East has taken root in Africa as well, causing chaos and bloodshed across a broad swath of the continent. 

Al Qaeda in the Islamic Maghreb, the terror group's African franchise, conquered a broad swath of northern Mali last year -- the first time an al Qaeda affiliate has ever taken and held terrain. AQIM also helped plan the siege of the American consulate in Benghazi that killed U.S. Ambassador Christopher Stevens and three other Americans. Other Islamist groups have carried out deadly attacks in Somalia, Algeria, and Niger. In Egypt, militants have launched a full-scale insurgency against security forces in the Sinai and begun striking Israel as well. 

Kenyan security forces may be close to retaking the mall and killing or capturing the last of the attackers. But the strike wasn't the first time militants have hit a target in Africa. And it will be far from the last.