Emily: You compare the rise of cyber weapons to the invention of the atomic bomb. Give us the lay of this new battlefield. Where are the biggest threats? And who are they coming from?

David Sanger: Well, the first comparison I do, Emily, is actually the invention of the airplane because when the airplane came in, and the Wright brothers first showed it to the military, their first response was, this is great. We'll put it up over the enemy troops. We'll see where their vulnerabilities are. And we'll send in the cavalry on horseback.

And it was about four years before people began dropping bombs with airplanes. And ultimately dropped the atomic bomb, the ultimate combination of technologies that gave them the reach and the power. For cyber, we're just at sort of that World War I period where we've gotten past the thought that cyber is just going to be used for surveillance.

We understand you can arm it. We understand you can blow up Iranian centrifuges with it and North Korean missiles. But we keep discovering other vulnerabilities that take us by surprise. And that's what the Russia hack was all about. I mean, just think. The election system was not on the Department of Homeland Security's list of 18 areas of critical infrastructure. The underpinning of our democracy, and it wasn't on the list.

Emily: So is that where the biggest threat is coming from? Is it Russia?

David Sanger: Well, the four big actors I discuss in this book among American adversaries are Russia, China, North Korea, and Iran. And of that group, the Russians are the savviest. The Chinese are the most determined, but less interested in destruction and more about theft of intellectual property and so forth. That may change over time.

And the Iranians and the North Koreans see it as a great leveler. The thing that they can use because they know that for all their pursuit of atomic weapons, they're never going to use an atomic weapon. They can't. They know what the next 45 minutes would look like, whereas cyber you can dial up, and you can dial down.

You mentioned the cyber command change in strategy, which is in the book. And I wrote a little bit about this in The Times earlier this week, just in an excerpt from the book. Here you have to think of sort of counterterrorism strategy.

For a while, we were saying, we're going to go inspect everything coming into the border to see if there's a bomb aboard a freighter or an airplane. And then in counterterrorism strategy post 9/11, we started knocking down houses in Pakistan where you thought the bomb makers were at work. That's what cyber command wants to do here. They want to go to a place where they think code is being developed, that is being designed to attack the United States. The problem is, you take that out, and the country you've hit says, well, wait a minute. We were just doing coding for a kindergarten through third grade educational software.

Emily: So US infrastructure has been undermined, attacked. We're heading into the midterms. Is this happening now? Is it going to keep happening? Our election is going to be undermined again?

David Sanger: Well, good question. One thing that helps when you're worrying about undermining elections is this time, Americans know a little bit about what this looks like from the Russia hack. Doesn't mean it will look the same way the next time. But in France with the warning of what happened to us, the fake Facebook posts and all that didn't have whole lot of effect because people were identifying it as coming from Russia.

What worries me about our next election, not just 2018, but 2020, is there will be other countries that will learn from what the Russians did and will devise new approaches. And the constant problem in cyber is you're always behind the eight ball. The attackers are always thinking of new ways in, which is why you're seeing new defense technologies that look at sort of behavior instead of just past patterns. But we also need to begin to think about what the geopolitical solution is to this.

Emily: How vulnerable, even though they have new information, is Facebook to being turned into a weapon again?

David Sanger: Less vulnerable than they were two years ago when they were clueless--

Emily: But as you say--

David Sanger: --on this.

Emily: --they move.

David Sanger: They do move. And I spent a lot of time in this book talking to people at Facebook. You'll see Alex Stamos talk--

Emily: Right, former head security officer who is no longer the head of security.

David Sanger: Yeah, I think he's still at Facebook, but--

Emily: For now.

David Sanger: Yeah, for now. But he-- really brilliant guy, but he made the point that the reason they missed the hacks was that they weren't looking for them. They didn't actually understand the behavior on their platform. And that could certainly happen again.