Editor's note: @BBC Africa correspondent Tomi Oladipo is reporting more than 20 police officers dead in an overnight ambush in Garissa, Kenya, citing local media reports. Al-Shabaab militants are the suspected attackers. In a conflicting report, a police spokesman says 13 officers are missing and two wounded. Kenya's Interior Ministry is denying the media reports of a death toll, and has reported five officers as wounded, with one in critical condition. We'll update as the situation becomes clearer. - Rebecca
Harakat al-Shabaab al-Mujahideen (HSM) (Arabic: حركة الشباب المجاهدين; Ḥarakat ash-Shabāb al-Mujāhidīn, Somali: Xarakada Mujaahidiinta Alshabaab, "Mujahideen Youth Movement" or "Movement of Striving Youth"), more commonly known as al-Shabaab (Arabic: الشباب), meaning "The Youth", or "The Youngsters", is a jihadist terrorist group based in Somalia. In 2012, it pledged allegiance to the militant Islamist organization al-Qaeda. As of 2013, the group has retreated from the major cities, but imposes strict forms of Sharia law in some rural regions. Al-Shabaab's troop strength as of 2013 was estimated at 4,000 to 6,000 militants. In February 2012, some of the group's leaders quarreled with Al-Qaeda over the union, and quickly lost ground.
The group is an off-shoot of the Islamic Courts Union (ICU), which splintered into several smaller factions after its defeat in 2006 by the Somali Transitional Federal Government (TFG) and the TFG's Ethiopian military allies. Al-Shabaab describes itself as waging jihad against "enemies of Islam", and is engaged in combat against the TFG and the African Union Mission to Somalia (AMISOM).
Alleging ulterior motives on the part of foreign organizations, group members have also reportedly intimidated, kidnapped and killed aid workers, leading to a suspension of humanitarian operations and an exodus of relief agents. Al-Shabaab has been designated a terrorist organization by several Western governments and security services.
As of June 2012, the US State Department has open bounties on several of the group's senior commanders.
In early August 2011, the TFG's troops and their AMISOM allies reportedly managed to capture all of Mogadishu from the al-Shabaab militants. An ideological rift within the group's leadership also emerged in response to pressure from the recent drought and the assassination of top officials in the organization. Due to its Wahhabi roots, Al Shabaab is hostile to Sufi traditions and has often clashed with the militant Sufi group Ahlu Sunna Waljama'a. The group has also been suspected of having links with Al-Qaeda in Islamic Maghreb and Boko Haram. The group has attracted some members from western countries, notably Samantha Lewthwaite and Abu Mansoor Al-Amriki.
Al-Shabaab has also been accused of being responsible for the deaths of tens of thousands of elephants every year for their ivory, and for killing rangers hired to protect them. The proceeds from the ivory trade allegedly supply Al-Shabaab with income with which to carry out their operations. At the same time, the group also had some social support during its time in administration within Somalia as it partook in some reforms.
In August 2014, the Somali government-led Operation Indian Ocean was launched to cleanup the remaining insurgent-held pockets in the countryside. On 1 September 2014, a U.S. drone strike carried out as part of the broader mission killed Al-Shabaab leader Moktar Ali Zubeyr. U.S. authorities hailed the raid as a major symbolic and operational loss for Al-Shabaab, and the Somali government offered a 45-day amnesty to all moderate members of the militant group. Political analysts also suggested that the insurgent commander's death will likely lead to Al-Shabaab's fragmentation and eventual dissolution.