Ever since 9/11, homeland security and counterterrorism professionals have been kept up at night by knowing that the odds against us are overwhelming. They have to "get it right" day in and day out; terrorists need to succeed only once and the consequences of even one strike can be devastating. Thomas Bossert, new Homeland Security and Counterterrorism Adviser, talks with David Sanger from the New York Times, about how he wrestles with this elemental struggle.