Snowden revelations: What more does he have?

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In a pair of interviews this weekend, a key journalist involved in reporting on Edward Snowden's revelations about US spying activities offered new insights into the data the former National Security Agency contractor has yet to reveal – and what sort of leverage he has to dissuade the US from acting against him.

Glenn Greenwald, a columnist for the Guardian and one of the first to report on Mr. Snowden's information, told the Associated Press over the weekend that the ex-contractor has "literally thousands of documents" that are ‘‘basically the instruction manual for how the NSA is built.’’

‘‘In order to take documents with him that proved that what he was saying was true he had to take ones that included very sensitive, detailed blueprints of how the NSA does what they do,’’ the journalist said Sunday in a Rio de Janeiro hotel room. ...

Greenwald said he believes the disclosure of the information in the documents would not prove harmful to Americans or their national security, but that Snowden has insisted they not be made public.

‘‘I think it would be harmful to the U.S. government, as they perceive their own interests, if the details of those programs were revealed,’’ he said.

Snowden is thought still to be in the transit zone of Moscow's Sheremetyevo airport, where he arrived some three weeks ago from Hong Kong and has remained since. On Friday, he attended a meeting with a number of Russian lawyers and human rights officials and announced that he would seek temporary asylum in Russia until he is able to find a secure route to Latin America, where several countries have offered him permanent asylum. Snowden was photographed at the meeting looking thin but healthy.

Mr. Greenwald told AP that Snowden remains "concerned" about his well-being, "but he’s not going to be in any way paralyzed or constrained in what he thinks he can do as a result of that." Greenwald also addressed the measures that Snowden has taken to dissuade those seeking to harm him for his disclosures, including a much rumored "dead man's switch" that would automatically release more sensitive documents should he be incapacitated.

‘‘It’s not just a matter of, if he dies, things get released, it’s more nuanced than that,’’ Greenwald said. ‘‘It’s really just a way to protect himself against extremely rogue behavior on the part of the United States, by which I mean violent actions toward him, designed to end his life, and it’s just a way to ensure that nobody feels incentivized to do that.’’

In a separate interview published over the weekend, reports Reuters, Greenwald said that publication of Snowden's data in toto would be the US government's "worst nightmare" – suggesting the import of the unreleased documents.

"Snowden has enough information to cause harm to the U.S. government in a single minute than any other person has ever had," Greenwald said in an interview in Rio de Janeiro with the Argentinian daily La Nacion.

"The U.S. government should be on its knees every day begging that nothing happen to Snowden, because if something does happen to him, all the information will be revealed and it could be its worst nightmare."

Greenwald also told the AP that he expects to continue publishing stories on US espionage activities over the next four months. While Snowden has offered to abide by Russian President Vladimir Putin's request that he "stop his work aimed at harming our US partners" in exchange for temporary asylum, Greenwald already has material in hand that he plans to use in future articles.

Upcoming stories would likely include details on ‘‘other domestic spying programs that have yet to be revealed,’’ but which are similar in scope to those he has been reporting on. He did not provide further details on the nature of those programs.