A few things become concerning with the information coming out.   At the top of that list comes the fact most of the terrorists *travelled to* the country to carry out the attack passing through multiple security levels.
New York Times […]  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 employee, officials say. At least one militant had 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, which killed scores of people over the weekend. After a four-day standoff, President Uhuru Kenyatta of Kenya claimed Tuesday to have finally “ashamed and defeated our attackers,” declaring that the last militants still holed up inside the mall had been killed, though the bodies of many civilians, perhaps dozens, had yet to be recovered.  (read more)