In the fifteen years since 9/11, America has launched two ground wars, lost 6,500 soldiers, and spent $1.8 trillion on war and another trillion on security at home. 

Yet, earlier this year, a poll conducted by the Chicago Council on Global Affairs showed that 42% of Americans feel less safe than they did on September 10, 2001.

To Juliette Kayyem, homeland security expert and host of the "Security Mom" podcast, that number suggests that the dialogue around what it means to be 'secure' needs to be reframed.

"We're never going to be 'safe,' but we have gotten safer," she said. 

Instead of thinking of safety as a finish line that can be definitively crossed, Kayyem says we should evaluate national security by a series of benchmarks: Do our investments in safety and security minimize all risks, not just terrorism? Do they maximize national defenses? Do they follow the Constitution and the spirit of the nation?

Instead of thinking of safety as a finish line that can be definitively crossed, Kayyem says we should evaluate national security by a series of benchmarks: Do our investments in safety and security minimize all risks, not just terrorism? Do they maximize national defenses? Do they follow the Constitution and the spirit of the nation?

"Those—combined with fits and starts and bad mistakes made and errors still occurring and gaps to be filled—I think, overall, the narrative of fifteen years is that we are safer," she said.

That narrative wasn't linear. Kayyem pointed to major security lapses in the response to Hurricane Katrina in 2005 as a wake-up call that the idea of 'homeland security' needed to encompass risks far beyond terrorism, like natural disasters.

"It reminded us we're a nation that was going to face more risk than just nineteen guys getting on an airplane, as horrible as that was," she said.

"We're much safer from the kind of catastrophic terrorism we saw on 9/11, but we will always have this persistent, low-grade threat," she continued.  "That is manageable. It is not existential."

To hear more from Juliette Kayyem, tune in to Boston Public Radio.