September 10, 2001: NSA Monitors Call as 9/11 Mastermind KSM Gives 9/11 Hijacker Atta Final Approval to Launch Attacks

9/11 hijacker Mohamed Atta calls 9/11 mastermind Khalid Shaikh Mohammed (KSM) in Afghanistan. KSM gives final approval to Atta to launch the attacks. The specifics of the conversation haven’t been released. [Independent, 9/15/2002] Unnamed intelligence officials later tell Knight Ridder Newspapers that the call is monitored by the NSA, but only translated after the 9/11 attacks. KSM, “using coded language, [gives] Atta final approval” for the attacks. [Knight Ridder, 9/9/2002] NSA monitored other calls between KSM and Atta in the summer of 2001 but did not share the information about this with other agencies (see Summer 2001). Additionally, it will later be revealed that an FBI squad built an antenna in the Indian Ocean some time before 9/11 with the specific purpose of listening in on KSM’s phone calls, so they may have learned about this call to Atta on their own (see Before September 11, 2001).