http://www.washingtonpost.com/wp-dyn/articles/A31951-2004Aug1.html
Such sophistication of planning is a hallmark of al Qaeda. At the U.S. embassy bombings trial in 2001, Jamal Amed al-Fadl, a former associate of Osama bin Laden's, testified that similar surveillance took place four years before the embassies in Kenya and Tanzania were bombed in 1998. Testimony showed that a team arrived in Nairobi in 1994, headed by Ali Mohammed, a former U.S. Army Green Beret now in prison, who had taught surveillance to al Qaeda recruits in Afghanistan training camps.
The team photographed buildings; analyzed access routes, building entrances and guard stations; and kept track of crowd flow around the embassy and other buildings in the area. Surveillance reports were sent to Afghanistan for review by bin Laden and Muhammad Atef, then his chief military planner. Atef, who made one visit to Kenya to review the scene, was killed in November 2001 during a U.S. bombing raid in Afghanistan.
There was no indication of when an attack might occur, though federal officials said it would likely be in the “near term.”