“In the book I talk about aliens and chemtrails and things like that, and the fact that there’s no evidence for that. I went looking on the network. I know, Joe, you want there to be aliens,” Snowden told the host of “The Joe Rogan Experience” in an episode released Wednesday.

“I do,” Rogan agreed.

“There probably are, right? But the idea that we’re hiding them — if we are hiding them — I had ridiculous access to the networks of the NSA, the CIA, the military, all these groups, I couldn’t find anything,” Snowden said. “So if it’s hidden, and it could be hidden, it’s hidden really damn well, even from people who are on the inside.”

In 2013, Snowden, an NSA contractor who had previously worked for the CIA, leaked to journalists thousands documents pertaining to classified global and domestic mass surveillance programs. Revelations from Snowden’s documents include the government’s ability to directly access Google accounts, millions of Verizon call records passed to intellligence agencies and widespread spying on the citizenry and leaders of dozens of countries, including close allies.

“I saw something wrong. I saw that, basically, the government was violating the law and what I believed to be the Constitution of the United States, more broadly human rights, for everyone in the United States and around the world,” Snowden told Rogan. “There were domestic surveillance programs. There were mass surveillance programs that worked internationally. Basically, everything they could monitor, they were monitoring.”

Snowden described to Rogan how he believes the intelligence community could have prevented the 9/11 attacks, but failed due to territoriality between agencies and the resulting “stovepiping” of databases that kept information sequestered. After the attacks, the intelligence agencies massively expanded their capabilities and reduced oversight, citing legal restraints as the reason behind intelligence failures leading up to the attacks — a claim Snowden described as “bull–it.”

“In a moment of fear, we lost our heads, and we abandoned all the traditional Constitutional restraints that we put on these agencies. And we abandoned all the traditional political restraints, and political restraints — ideological systems of belief about the limitations the secret police should have in a free and open society.”

But while Snowden grew skeptical of not only intelligence agency methods, but also their motives, he cautioned against believing in conspiracy theories that require secret, mass coordination.

“Everyone wants to believe in conspiracy theories because it helps life make sense. It helps us believe somebody is in control, somebody is calling the shots,” Snowden said. “There are real conspiracies, but they don’t typically have tens of thousands of people working on them, unless you’re talking about the existence of the intelligence community itself, which is basically constructed on the idea — I think there’s 4 million people in the United States who hold security clearances — that you can get all of those people to not talk, ever, to journalists.”

Snowden said he was inspired to appear on “The Joe Rogan Experience” after Democratic presidential candidate Senator Bernie Sanders appeared on the show in August, in part to draw attention to the government’s lawsuits against his new book, Permanent Record, which he described as an ongoing effort in “financial censorship.”

“They don’t want to see books like this getting written,” Snowden said.