“It’s kind of Darwinian,” former National Security Agency Director Michael Hayden said. “The more stuff like this is in the public domain, we’ll still catch terrorists, but it will be the stupid terrorists. … The guys we should really be worried about will be far less likely to be swept up in this effort.”

While many Americans view terrorists as careful and well-informed, ex-intelligence officials say that in reality, their skill sets run the gamut — and the biggest terror threat in the United States right now actually seems to be homegrown extremists who are not hardened operatives and who lack first-rate tradecraft. These are the precisely the sorts of novices who could be tipped off or decide to behave more furtively precisely because of the recent spate of surveillance disclosures.

And, as Americans saw in April with the deadly attacks Tamerlan and Dzhokhar Tsarnaev allegedly carried out at the Boston Marathon, amateurs are still capable of inflicting serious damage.

“Intelligence agencies make a living off of other people’s mistakes,” said former NSA general counsel Joel Brenner. “You’d be surprised at how many people make mistakes.”…

The impact, said Hayden, is magnified over time. “The more it’s public, it goes viral. It’s networked. It spreads throughout the network,” the former NSA chief added. “There may have been nodes in the network that were quite aware and nodes in the network that weren’t. That proportion is going to change.”