The NSA was listening in on the hijackers calls for years before 9/11, but failed to trace them in the US and notify the FBI (at the same time the CIA was also repeatedly failing to notify the FBI allegedly due to a bizarre string of coincidences). The number they were talking to was registered to Ahmed al-Hada, a close associate of bin Laden who was involved in the embassy and Cole bombings. The failure was repeated several times over an approximately 18 month period. If people knew this, they Hayden would be in for a really rough time.