Kenyan mall siege took al-Shabab months of meticulous planning
Officials left wondering how Islamist extremists could take over a mall with military-grade weapons, then hold off security forces for days
The plot was hatched weeks or months ago on Somali soil by al-Shabab's "external operations arm", officials say. A team of English-speaking foreign fighters was carefully selected, along with a target: Nairobi's gleaming Westgate mall.
The building's blueprints were studied, down to the ventilation ducts. The attack was rehearsed and the team dispatched, slipping undetected through Kenya's porous borders, often patrolled by underpaid - and deeply corrupt - border guards.
A day or two before the attack, powerful belt-fed machine guns were secretly stashed in a shop in the mall with the help of a colluding worker. At least one militant even packed a change of clothes so he could slip out with fleeing civilians after the killings were done.
That is the picture emerging from American security officials of the massacre at the Westgate mall that killed scores of people over the weekend. After a four-day stand-off, President Uhuru Kenyatta of Kenya claimed on Tuesday to have finally "ashamed and defeated our attackers". He declared that the last militants still holed up inside the mall had been killed, though the bodies of many civilians, perhaps dozens, have yet to be recovered.
Kenyatta said that "intelligence reports had suggested that a British woman and two or three American citizens may have been involved", but that he could not confirm those reports. American officials said they had not yet determined the identities of the attackers but did know the massacre had been meticulously planned to draw "maximum exposure".
"They had people in there, they had stuff inside there," said an American security official. "This was all ready to go when the shooters walked in."
Kenya is holding three days of mourning to mark one of the most unsettling episodes in its recent history. The authorities of a country perceived as an oasis of peace and prosperity in a troubled region are struggling to explain how 10 to 15 Islamist extremists could lay siege to a shopping mall, killing more than 60 civilians with military-grade weaponry, then hold off Kenyan security forces for days.
Several times the government said the mall was under its control, only to have fighting burst out again.
Western security officials fear that several fighters slipped out of the mall during the mayhem, dropping their guns and disguising themselves as civilians, an account echoed by some witnesses.
Video: Mall seige ends, mourning begins
The way the attack was carried out may have had something to do with the recent killing of Omar Hammami, an al-Shabab fighter who grew up in the US state of Alabama and became a phantom-like figure across the Somali deserts, known by his nom de guerre: Abu Mansoor Al-Amriki, "the American".
Hammami was fatally shot by another wing of al-Shabab less than two weeks ago.
One reason for the rift was Hammami's complaints that al-Shabab had become too brutal towards fellow Muslims under the leadership of the group's emir, Ahmed Abdi Godane.
Stig Jarle Hansen, a Norwegian researcher who has published a book on al-Shabab, said this rift might explain why the militants in the Nairobi mall decided to spare the lives of many Muslims.
"Even Osama bin Laden criticised Godane for being too harsh," Hansen said. "This attack might have been Godane's way of saying, 'See, I'm not so harsh - to Muslims'."
American officials say al-Shabab may have recruited English speakers from the US and possibly other Western countries so they would be able to operate effectively in Kenya, where English and Swahili are the national languages.