Al-Shabaab Claims Credit For Uganda Bombing: Background, History

In the Somali capital, Mogadishu, a top spokesman for the hardline al-Shabab said the group carried out the bombings, and he threatened further attacks if Uganda and Burundi continued to supply troops to an African Union peacekeeping force in Somalia.
"Al Shabab was behind the blasts," Ali Mohamud Raghe, the militia's spokesman told reporters. "Thanks to our martyrs who carried out the attacks."

The group is an off-shoot of the Islamic Courts Union, which splintered into several smaller groups after its removal from power by Ethiopian forces in 2006.[5] The group describes itself as waging jihad against "enemies of Islam" and is engaged in combat against the Somali Transitional Federal Government (TFG) and African Union Mission to Somalia (AMISOM). It has reportedly "declared war on the U.N. and on Western non-governmental organizations" that distribute food aid in Somalia, killing 42 relief workers in the past two years of 2008 and 2009.[3] It has been designated a terrorist organization by several western governments and security services,[6][7][8] and described as having "ties to Al Qaeda,"[3] which their leaders denied until early 2010.

Shabaab is nominally led by Sheikh Mohamed Mukhtar Abdirahman "Abu Zubeyr," though experts say a core group of senior leaders guide its actions. The group is divided into three geographical units: Bay and Bokool regions, led by Mukhtar Roobow "Abu Mansur," the group's spokesman; south-central Somalia and Mogadishu; and Puntland and Somaliland. A fourth unit, which controls the Juba Valley, is led by Hassan Abdillahi Hersi "Turki," who is not considered to be a member of Shabaab, but is closely aligned with it.