“One of the documents stored on the al Qaeda computer recovered by the Wall Street Journal after the fall of the Taliban was a letter from [al Qaeda second-in-command] Ayman al Zawahiri to [al Qaeda military commander Mohammed Atef, aka] Abu Hafs, dated April 15, 1999, an excerpt of which follows. ‘The enemy [the West] started thinking about these [chemical and biological] weapons before World War I. Despite their extreme danger, we only became aware of them when the enemy drew our attention to them by repeatedly expressing concerns that they can be produced simply with easily available materials.’ ”
– Peter Bergen, The Osama bin Laden I Know, Page 343