Amy Zegart has a new book: Spies, Lies, and Algorithms: The History and Future of American Intelligence. Wired has an excerpt:

In short, data volume and accessibility are revolutionizing sensemaking. The intelligence playing field is leveling­ — and not in a good way. Intelligence collectors are everywhere, and government spy agencies are drowning in data. This is a radical new world and intelligence agencies are struggling to adapt to it. While secrets once conferred a huge advantage, today open source information increasingly does. Intelligence used to be a race for insight where great powers were the only ones with the capabilities to access secrets. Now everyone is racing for insight and the internet gives them tools to do it. Secrets still matter, but whoever can harness all this data better and faster will win.

The third challenge posed by emerging technologies strikes at the heart of espionage: secrecy. Until now, American spy agencies didn’t have to interact much with outsiders, and they didn’t want to. The intelligence mission meant gathering secrets so we knew more about adversaries than they knew about us, and keeping how we gathered secrets a secret too.

[…]

In the digital age, however, secrecy is bringing greater risk because emerging technologies are blurring nearly all the old boundaries of geopolitics. Increasingly, national security requires intelligence agencies to engage the outside world, not stand apart from it.

I have not yet read the book.