Insider recently obtained an advance copy of "Life Undercover: Coming of Age in the CIA," a new book out Tuesday by Amaryllis Fox, a former clandestine services officer.

In an interview, Fox disclosed the threat that keeps her awake at night: political divisions that are weakening the US from the inside.

Fox's new book, a memoir of her life in the CIA, details various interactions and exchanges, as well as the lessons she learned about how to secure peace through genuine human connection, even if only for one more day, in the face of loose weapons of mass destruction, extremism, and hate.

She said she felt a "responsibility to share this story as our own domestic conversation nationally began to disintegrate and our ability to find common ground and climb inside one another's perspectives here at home seemed to be evaporating."

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This former CIA spy knows well the dangers lurking in the shadows, but the one threat that keeps her awake at night is not what you might think.

"There are many existential threats out there," Amaryllis Fox, a former clandestine services officer who worked to prevent terrorists from getting their hands on weapons of mass destruction, told Insider. "But the security challenge that keeps me up at night now is the divisions that we are facing domestically and with our allies."

In recent years, the US has become much more politically divided on a wide variety of issues, and US alliances have been weakened as the Trump administration undermines NATO, distances itself from fractures in the East Asian security architecture, and outright abandons allies elsewhere.

Fox said that adversarial powers like Russia were exploiting these weaknesses — the one thing, she explained, that "has the potential to destroy us as a country."

"There are so many potential military and terror threats out there, but anytime we face one of those, we have the most capable military and intelligence infrastructure in the world to respond," she told Insider. "But when you look at the division that is weakening our house, I'm not sure we have the national security resources to respond."

It was in response to this serious threat that Fox decided to write "Life Undercover: Coming of Age in the CIA," a memoir of her years in the CIA and a recollection of the lessons she learned — the hard way, in some cases — that she felt might help the US heal.

"I really started to feel the responsibility to share this story as our own domestic conversation nationally began to disintegrate and our ability to find common ground and climb inside one another's perspectives here at home seemed to be evaporating," she told Insider.

Having experienced the pain of terrorism, most directly when a bomb aboard Pan Am Flight 103 killed her best friend and 269 others in Lockerbie, Scotland, in 1988, Fox joined the CIA after 9/11 as a young officer determined to wipe players off the field.

"It was over the course of my career and my personal growth that I learned that this just doesn't really work," she said. "Not only is it not a fulfilling way to live, but when you set out to crush the adversary, you often risk creating more enemies than you destroyed.

"That was a lesson that took me some time and many interactions to kind of have knocked into me," Fox added.

One such exchange was in Karachi, Pakistan, with representatives from three extremist groups whom she was there to dissuade from carrying out a catastrophic attack — a critical meeting where failure might have resulted in not only the loss of her life but the deaths of thousands of others.

Sitting across from the "feared and battle-hardened jihadi," as she described the chief negotiator in her book, Fox first tried to approach the matter directly, but with no success.

Too much blood had been shed on both sides.

A day before the meeting, one of Fox's friends was killed in a bombing in Afghanistan.

But rather than let hate and anger overwhelm her, Fox, the mother of a 1-year-old girl, approached the man, who was holding a wheezing 4-month-old child in his arms, as a human being, as a parent.

They bonded, albeit hesitantly, over clove oil, a home remedy for breathing problems, among other things.

In that moment of authenticity among all the spy games and deception and war, Fox persuaded the extremists to call off their planned attack, knowing that all sides would pick new targets and that the board would be reset for another high-stakes game.

"Could we try and save humankind today? Even if it destroys itself again tomorrow?" she asked. The man agreed.

In her new book, Fox shares several interactions like this — experiences that she hopes will help teach an important lesson.

"When I saw us domestically in this country begin to lose the ability to even listen to our friends and neighbors, let alone the people who are trying to kill us, it seemed that it would be valuable to share some of these interactions and let people take from my personal journey what they might have taken if they had had some of the same interactions themselves," she said.

She told Insider that "the greatest act of patriotism any of us can engage in right now is trying to find common ground and not allow our adversaries to weaken us from the inside out."

This is how she sees the US confronting the one threat that keeps her awake at night. As for the rest of the threats, her advice is to trust the professionals.

"I can't lie and say that they are not out there, because they certainly are," Fox told Insider. She added that most Americans "would be overwhelmed" if they knew just how many threats were being tackled behind the scenes every day, but that there are men and women working tirelessly in secret to protect this country and keep people safe from harm.