NAIROBI – The alleged Somali mastermind of the assault on a posh mall that killed scores and jolted Kenya is a man of contradictions.

Ahmed Godane is bookish, eloquent in both Arabic and Somali, recites poetry and is known to quote from obscure academic journals, analysts say. Yet he trained and fought in Afghanistan for the jihadist cause and has ruthlessly killed most of his rivals to seize control of al-Shabab, a Somali militia linked to al-Qaida that has asserted responsibility for the Westgate Mall attack.

Al-Shabab has said the assault, which began Saturday, was revenge for Kenya sending troops into Somalia. But the carnage had just as much to do with the struggles inside the militia and Godane’s desire to make al-Shabab — and himself — stronger and more relevant in the global jihad against the United States and its allies, according to analysts.

Late Wednesday night, in an audio message posted on a website linked to al-Shabab, Godane warned the Kenyan government of more attacks if it refuses to withdraw its forces. “Take your troops out or prepare for a long-lasting war, blood, destruction and evacuation,” Godane said, according to a translation by the Reuters news agency.

The four-day siege of the Westgate Mall was Godane’s first major cross-border assault since he eliminated key al-Shabab leaders in the summer and solidified his grip over the militia. His ambitions appear to be as complex as his personality.

“Godane is clearly positioning himself as the next Anwar al-Awlaki — on top of his game as the head of a local al-Qaida affiliate, and with international ambitions,” said Abdi Aynte, director of the Heritage Institute for Policy Studies, a Mogadishu-based think tank. He was referring to the Yemeni American preacher who was a key figure in al-Qaida’s Yemen branch and was killed in a 2011 U.S. drone strike.

Since 2011, al-Shabab has lost much territory in Somalia, pushed out of key cities by Western-backed African Union forces and weakened by infighting and loss of funding.

An ideological and directional split among the militia’s leaders pitted nationalists, who want the group to remain focused on ousting Somalia’s government, against transnationalists such as Godane, who have been pushing for a wider jihadist agenda, regionally and beyond.

After a brutal struggle, Godane emerged victorious. He transformed the militia into a more streamlined, unified and radicalized terrorist force, said J. Peter Pham, head of the Africa Center at the Atlantic Council. In some ways, the mall attack was an announcement to radical Muslims and the West that a new al-Shabab had arrived — with Godane in control.

“The attack was Godane’s way of solidifying his recent quelling of internal dissent and firmly placing the organization as a global jihadist entity,” Aynte said.

Al-Shabab’s larger footprint under Godane comes as al-Qaida’s central branch in Pakistan and Afghanistan is increasingly diminished. It is relying more heavily on local and regional terrorist affiliates — in western, northern and eastern Africa, the Arabian Peninsula and other areas — to spread its philosophies and target the West and its allies.

Analysts say al-Qaida and al-Shabab are forging a symbiotic relationship, and some think the well-planned attack on the mall could not have been accomplished without al-Qaida’s assistance.

“For al-Qaida central to have more reach, when its assets are diminished, it has to rely more and more on regional affiliates,” said Cedric Barnes, Horn of Africa director for the International Crisis Group, a think tank. “Godane needs the legitimacy al-Qaida provides. He doesn’t have the kind of senior authority in the wider jihadi world.”

That is what Godane has craved for years, analysts say.

Godane, thought to be in his mid-30s, is from the city of Hargeisa in the breakaway region of Somaliland. As a child, he attended Islamic school and performed so well that he won a scholarship to study in Sudan.

In the 1990s, he earned another scholarship, this time to study in Pakistan. It was there that he connected with jihadist circles, analysts say, traveling to Afghanistan to train and fight, as well as to Kashmir, the Himalayan region contested by India and Pakistan.

By 2002, Godane was back in Somalia and had joined the Islamic Courts Union, an Islamist group that controlled large swaths of southern Somalia. He held senior positions until late 2006, when the transitional government backed by Ethiopian troops drove the Islamists out. Hard-liners from the group then formed al-Shabab, which in Arabic means “the Youth.” By 2007, Godane had joined the militia and started to rise up its ranks.

According to Stig Jarle Hansen, a Norwegian analyst who wrote a book about al-Shabab, Godane has been implicated in several attacks against Westerners in Somaliland, including the killing of a British couple and an attack on a German aid organization.

On May 2, 2008, a U.S. Tomahawk cruise missile killed al-Shabab’s supreme leader, Aden Hashi Ayro, throwing the militia in disarray. Within months, Godane had taken control of the group. In early 2010, he announced that al-Shabab would formally align with al-Qaida.

At the time, al-Shabab was a large, loosely knit collection of cells. There were many powerful commanders who rivaled Godane in influence and respect — and not everyone agreed with his internationalist vision or tactics.

In areas that the militia controlled, Godane imposed strict Islamic law enforced by public executions, amputations and stonings. The measures were so harsh, Hansen said, that even Osama bin Laden criticized him for going too far in implementing Shariah law and for killing other Muslims.

That and other complaints about strategy and the treatment of foreign fighters prompted al-Shabab leaders to challenge Godane. But he assassinated or marginalized his rivals. The latest casualty was Omar Shafik Hammami, a well-known American commander from Alabama known as Abu Mansoor al-Amriki, who was the militia’s chief propagandist. He was killed this month by Godane loyalists.

In tweets before he was killed, Amriki said Godane “has gone mad.” In his last interview, with Voice of America, Amriki called Godane “a control freak,” which security experts say may account for the sophistication of the mall attack, which probably took months to plan.

The complaints about Godone might also help explain why the militants involved in the attack sought to avoid targeting Muslims, according to witnesses. Godane, who needs the legitimacy of al-Qaida, did not want to anger or alienate radical Muslims or senior jihadists in the terrorist network, Hansen said.

The siege of the Westgate Mall also came a few days after al-Qaida leader Ayman al-Zawahiri issued a guideline for waging jihad, in which he instructed fighters not to target Muslims and to take as hostages the citizens of nations that have invaded Muslim countries.

Hansen predicts that Godane will continue to strike at targets in the region but will keep working closely with al-Qaida. “And I think al-Qaida kind of agrees with this priority,” he said.