Q&A: Who are Somalia's al-Shabab?
Somalia's al-Shabab, which has carried out the deadly attack on a shopping centre in neighbouring Kenya, is linked with al-Qaeda. It has been pushed out of all of the main towns it once controlled in southern and central parts of Somalia, but still remains a potent threat.
Who are al-Shabab?
Al-Shabab means The Youth in Arabic. It emerged as the radical youth wing of Somalia's now-defunct Union of Islamic Courts in 2006, as it fought Ethiopian forces who had entered Somalia to back the weak interim government.
There are numerous reports of foreign jihadists going to Somalia to help al-Shabab and it has formed links with al-Qaeda.
It is banned as a terrorist group by both the US and the UK and is believed to have between 7,000 and 9,000 fighters.
It has imposed a strict version of Sharia law in areas under its control, including stoning to death women accused of adultery and amputating the hands of thieves.
How much of Somalia does al-Shabab control?
Al-Shabab At A Glance
- "The Youth" in Arabic
- Formed as a radical offshoot of the Union of Islamic Courts, which controlled Mogadishu, in 2006
- Previously ran much of southern Somalia
- Lost some popular support by banning Western aid agencies during 2011 famine
- Estimated to have 7,000 to 9,000 fighters
- Announced merger with al-Qaeda in 2012
Although it has lost control of the towns and cities, its writ still runs in many rural areas.
It was forced out of the capital, Mogadishu, in August 2011 and left the vital port of Kismayo in September 2012.
Kismayo had been a key asset for the militants, allowing supplies to reach areas under their control and providing taxes for their operations.
The African Union (AU), which is supporting government forces, hailed both as major victories, however al-Shabab still carries out fairly frequent suicide attacks in Mogadishu and elsewhere.
Analysts believe al-Shabab is increasingly focusing on guerrilla warfare to counter the firepower of AU forces.
But the group is under pressure on several fronts following Kenya's incursion into Somalia in 2011. Kenya accused al-Shabab fighters of kidnapping tourists, and its forces, now under the AU banner, have been in the forefront of the push against al-Shabab in the south up to Kismayo.
Meanwhile, Ethiopian forces moved in from the west and seized control of the central towns of Beledweyne and Baidoa.
Who is al-Shabab's leader?
Ahmed Abdi Godane is the head of the group. Known as Mukhtar Abu Zubair, he comes from the northern breakaway region of Somaliland.
Mr Godane is rarely seen in public. His predecessor, Moalim Aden Hashi Ayro, was killed in a US airstrike in 2008.
Mr Godane, who was behind the group's tie-up with al-Qaeda and has a hardline, international agenda has recently emerged victorious from an internal power-struggle.
His rival, Sheikh Hassan Dahir Aweys, is more focussed on the struggle within Somalia. He is now in government custody, while several of his allies have been killed.
What are al-Shabab's foreign links?
Al-Shabab joined al-Qaeda in February 2012. In a joint video, al-Shabab leader Ahmed Abdi Godane said he "pledged obedience" to al-Qaeda head Ayman al-Zawahiri.
The two groups have long worked together and foreigners are known to fight alongside Somali militants.
US officials believe that with al-Qaeda on the retreat in Afghanistan and Pakistan following the killing of Osama bin Laden, its fighters will increasingly take refuge in Somalia.
There have also been numerous reports that al-Shabab may have formed some links with other militants groups in Africa, such as Boko Haram in Nigeria and al-Qaeda in the Islamic Maghreb.
Has al-Shabab carried out attacks outside Somalia?
Al-Shabab has said it carried out the deadly assault on a shopping centre in Nairobi on 21 September, in which at least 68 people were killed.
It was responsible for a double suicide bombing in Uganda's capital, Kampala, which killed 76 people watching the 2010 football World Cup final on television.
The attack was carried out because Uganda - along with Burundi - provided the bulk of the AU troops in Somalia before the Kenyans went in.
Analysts say the militants often enter and leave Kenya without being intercepted. Their fighters are said to even visit the capital, Nairobi, for medical treatment.
The 2002 twin attacks on Israeli targets near the Kenyan resort of Mombasa were allegedly planned in Somalia by an al-Qaeda cell, while the US believes some of the al-Qaeda operatives who carried out the 1998 attacks on its embassies in Nairobi and Dar es Salaam then fled to Somalia.
Who are al-Shabab's backers?
Eritrea is its only regional ally. It denies claims it supplies arms to al-Shabab.
Eritrea supports al-Shabab to counter the influence of Ethiopia, its bitter enemy.
With the backing of the US, Ethiopia sent troops to Somalia in 2006 to defeat the Islamists. The Ethiopian forces withdrew in 2009 after suffering heavy casualties.
After intervening again in 2011, it says it will hand over the territory it has seized to the AU.
What about the Somali government?
The president is a former academic and activist, Hassan Sheikh Mohamud. He was elected in 2012 by the newly chosen Somali parliament, under a UN-brokered peace process.
He defeated ex-President Sheikh Sharif Sheikh Ahmed - a former Islamist rebel fighter, whose three years in power were criticised by donors who said corruption was rife.
Al-Shabab has denounced the process as being a foreign plot to control Somalia.
Somalia is pretty much a failed state. It has not had an effective national government for about 20 years, during which much of the country has been a constant war-zone.
This made it easy for al-Shabab, when it first emerged, to win support among Somalis. It promised people security - something they welcomed.
But its credibility was knocked when it rejected Western food aid to combat the 2011 drought and famine.
Al-Shabab advocates the Saudi-inspired Wahhabi version of Islam, while most Somalis are Sufis. Al-Shabab has destroyed a large number of Sufi shrines, causing its popularity to further plummet.
However, with Mogadishu and other towns now under government control, there is a new feeling of hope in the country and many Somalis have returned from exile, bringing their money and skills with them.
With services such as dry cleaning and rubbish collection opening, maybe Somalia can finally re-emerge from the ashes of the past two decades.