The CIA was aware of Mihdhar and Hazmi 's involvement with al-Qaeda , having been informed by Saudi intelligence during a 1999 meeting in Riyadh . Based on information uncovered by the FBI in the 1998 United States embassy bombings case , the National Security Agency ( NSA ) began tracking the communications of Hada , Mihdhar 's father-in-law . In late 1999 , the NSA informed the CIA of an upcoming meeting in Malaysia , which Hada mentioned would involve " Khalid " , " Nawaf " , and " Salem " , who was Hazmi 's younger brother , Salem al-Hazmi
1998 United States embassy bombings
1998 United States embassy bombings
Khalid al-Mihdhar