Why America Failed to Stop 9/11 | Gerald Posner & Michael Shermer

How did 19 hijackers evade the world's most advanced intelligence apparatus despite years of warnings? Twenty-five years after 9/11, journalist Gerald Posner joins Michael Shermer to explain the security failures that left America vulnerable. Those failures, compounded by government secrecy, have helped sustain suspicions that officials orchestrated the attacks or deliberately allowed them to happen. What does the evidence show, and have we learned the right lessons?