Harakat al-Shabaab al-Mujahideen (HSM; Arabic: حركة الشباب المجاهدين, Ḥarakat ash-Shabāb al-Mujāhidīn; Somali: Xarakada Mujaahidiinta Alshabaab, lit. "Mujahideen Youth Movement" or "Movement of Striving Youth"), more commonly known as Al-Shabaab (Arabic: الشباب, lit. '"The Youth" or "The Youngsters"'), is a jihadist terrorist group based in East Africa. In 2012, it pledged allegiance to the militant Islamist organization Al-Qaeda. In February of the year, some of the group's leaders quarreled with Al-Qaeda over the union, and quickly lost ground. Al-Shabaab's troop strength was estimated at 7,000 to 9,000 militants in 2014. As of 2015, the group has retreated from the major cities, controlling a few rural areas.
Al-Shabaab is an offshoot of the Islamic Courts Union (ICU), which splintered into several smaller factions after its defeat in 2006 by Somalia's Transitional Federal Government (TFG) and the TFG's Ethiopian military allies. The group describes itself as waging jihad against "enemies of Islam", and is engaged in combat against the Federal Government of Somalia and the African Union Mission to Somalia (AMISOM). Al-Shabaab has been designated as a terrorist organization by Australia, Canada, the United Arab Emirates, the United Kingdom and the United States. As of June 2012, the US State Department has open bounties on several of the group's senior commanders.
In early August 2011, the Transitional Federal Government's troops and their AMISOM allies managed to capture all of Mogadishu from the Al-Shabaab militants. An ideological rift within the group's leadership also emerged, and several of the organization's senior commanders were assassinated. 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. Additionally, it attracted some members from western countries, notably Samantha Lewthwaite and Abu Mansoor Al-Amriki.
In August 2014, the Somali government-led Operation Indian Ocean was launched to clean up 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.