What You Need to Know About Terrorism in East Africa

A guide to the groups in and around Somalia contributing to the ongoing war on terrorism.

Recently trained  al-Shabab fighters stand during a military exercise in northern Mogadishu, Somalia on Jan. 1, 2010.

Fighters of Somalia's al-Shabab, whose name translates to "the youth," are one of several militant groups vying with government forces in East Africa.

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Mentioning Somalia used to conjur up images of pirates off the coast and the distant but stark memories from 1993 of clan militias dragging the bodies of dead U.S. commandoes through the streets of Mogadishu, brought to life in the movie "Black Hawk Down."

[READ: Kenya Mall Attack Could Signal New Rise of al-Qaida]

Now, the troubled Horn of Africa nation returns to the headlines following news at the end of September that a regional gang of thugs has now ballooned into a transnational terrorist organization.

Fully understanding the threats posed by al-Shabab, which continues attacks in the region and recruitment elsewhere, requires a better understanding of the area from which it was forged.

Check out this primer on the major groups in East Africa that are contributing the ongoing struggle between extremists and burgeoning governance.

Al-Shabab

There have been several iterations of the extremist group since it was founded early in this century. Aden Hashi Farah Ayro formed al-Shabab, whose name translates to "the youth," as an armed and more hardliner sect within the Islamic Courts Union, a collection of courts within Somalia designed to enforce Islam's Sharia law.

The ICU was attacked by a force of largely Ethiopian troops in December of 2006 and driven into exile, allowing Shabab to become the new umbrella organization for Islamic militancy in the region. That conflict also forged an anti-Ethiopian sentiment among its members.

A strong financial foundation from foreign actors, including al-Qaida groups, allowed al-Shabab to gain control from 2007 to 2011 of most of southern and central Somalia, as well as most of the capital Mogadishu and the port town of Kismayo.

Widespread famine throughout East Africa beginning in 2011, combined with a push from the African Union Mission in Somalia, or AMISOM, contributed to weakening al-Shabab's hold on these parts of the country. Dissension spread through its ranks, particularly among those who believed in the establishment of an Islamic state in Somalia.

[REPORT: Kenyan Authorities Were Warned of Mall Attack Threat]

This allowed the rise of Moktar ali Zubeyr, known under many aliases, as the new emir of the organization. He eliminated any member who contributed to this infighting or the marginalization of al-Shabab.

"It became much smaller but much more radical," says J. Peter Pham, the director of the Atlantic Council's Africa Center and frequent adviser to Congress and the White House.

"Clearly what they were doing is making a leaner, meaner Shabab that has shown itself to be a transnational terrorist organization," he says.

The goals of al-Shabab have shifted slightly as it moved from a localized fighting force into a Somali-based international extremist group. It is one of, if not the only Islamist terrorist organization to recruit and operate within the U.S. It forges lone wolf operators and may have actively recruited Somalis living in Minnesota to participate in the Sept. 21 assault on a mall in Nairobi, Kenya.

'Al-Qaida in East Africa'

This is a term used mostly by Western or Western-backed forces to describe Islamic militancy in the region outside of al-Shabab. It has not existed in the same, centric form as other groups, a defense official tells U.S. News, such as al-Qaida in the Islamic Maghreb (AQIM) and al-Qaida in the Arabian Peninsula (AQAP).

Al-Qaida affiliates such as these have, however, long been financial backers of al-Shabab. Many of its founding leaders have come from other al-Qaida syndicates or received training from them, and carried on many of the same governing principles. Among these is the basic tenet from founder Osama bin Laden, derived from his idol Egyptian Islamist Sayyid Qutb, of the ultimate goal of establishing an Islamic state independent of Western influence.

[PHOTOS: Dozens Killed in Attack on Kenyan Mall]

Bin Laden, however, was always hesitant to endorse al-Shabab. Experts on his brand of extremism, including the Atlantic Council's Pham, say the terrorist leader was speculative of whether Somalis were committed to the core causes of al-Qaida. And while he was alive, bin Laden never fully accepted them as a legitimate franchise.