There is evidence that some of al Qaeda's nuclear efforts over the years met with swindles and false leads.

Al Qaeda is closely aligned with the Chechens.

Counterterrorism analysts have known for years that al Qaeda prepares for attacks with elaborate 'targeting packages' of photographs and notes.

Searches of al Qaeda sites in Afghanistan, undertaken since American-backed forces took control there, are not known to have turned up a significant cache of nuclear materials.

Leaders at the top of al Qaeda's hierarchy, the evidence shows, completed plans and obtained the materials required to manufacture two biological toxins - botulinum and salmonella - and the chemical poison cyanide.

Unsettling signs of al Qaeda's aims and skills in cyberspace have led some government experts to conclude that terrorists are at the threshold of using the Internet as a direct instrument of bloodshed.