Pistole knows terrorists continue to plot new attacks. They nearly succeeded last Christmas Day when Umar Farouk Abdulmutallab tried to ignite a bomb concealed in his underwear as Northwest flight 253 approached Detroit.
At a Transportation Security Administration testing facility, Pistole gave CBS News an exclusive look at the type of powerful explosive used in the unsuccessful attack: Pentaerythritol tetranitrate, also know as PETN, which an al Qaeda bomb-maker had mixed with another explosive, TATP, to make the underwear bomb, reports CBS News Justice and Homeland Security correspondent Bob Orr.
"Where the passengers heard what they thought were firecrackers going off, that was actually the TATP initiating," says Pistole. "And by the grace of God and just good fortune, it did not detonate."
To test screeners and to stay ahead of the terrorists, TSA bomb experts such as Ed Kittel, chief of the explosives operations division, create their own improvised explosive devices: a Thermos with explosives in the liner and slippers hiding a shoe bomb.
"The whole bomb is in the slipper," says Kittel, explaining one of his devices. "In this case you just push a switch and it is a suicide-activated device."
Before taking control at TSA, Pistole spent 26 years at the FBI running major terror investigations. To prevent the next attack, he's pushing intelligence to screeners on the front lines.
"What I want to make sure is that we are not using old information to try to prevent old things from happening," he says. "Although we need to make sure another Sept. 11 doesn't happen."
Pistole says security measures will change as the threat evolves but some old dangers remain. For now, passengers must still remove their shoes and leave their water bottles behind.
The threat of a liquid being part of an explosive device is enough of a threat to justify limiting the liquids that come aboard each plane. When asked if he was apologizing for keeping liquids off planes, Pistole says, "Absolutely not."
For Pistole it's all about managing risk. There's no taking chances when terrorists only have to be right once.