Kaplan says the world has been closer to nuclear war than we realize, but it hasn't happened.
"For the most part, nuclear deterrence works," says Kaplan, "you attack us, we'll attack you. It gives people second thoughts."
Kaplan says several Presidents considered their use, evaluating the logic and outcomes and risk of using the weapons, "at the end of the day, they back away. They see this as leading to catastrophe and they find some other way out."
What about President Trump with his "fire and fury" comments directed toward North Korea?
Kaplan says at the time of Trump's remarks, "there was very serious warplans in the works for launching a first strike against North Korea. There were some situations where it did get very close to that point."
Fred Kaplan will be in St Louis on Thursday February 6, at 7pm at the St Louis County Library Headquarters.