Michael Hayden remembers Sept. 11, 2001 differently than most — he was tasked with ensuring such a day never happened to America again.

The retired U.S. Air Force general was the National Security Agency’s director from 1999 to 2005, directed the CIA from 2005 to 2009, and was a leading figure in the intelligence community’s response to the 9/11 attacks. Former President George W. Bush secretly launched the domestic NSA spying program Stellar Wind three weeks after the massacre, setting the stage for decades of legal and congressional battles.