The strategy employed by NSA whistleblower Edward Snowden to discourage a CIA hit job has been likened to a tactic employed by the U.S. and Russian governments during the Cold War.

Snowden, a former systems administrator for the National Security Agency in Hawaii, took thousands of documents from the agency's networks before fleeing to Hong Kong in late May, where he passed them to Guardian columnist Glenn Greenwald and documentary filmmaker Laura Poitras. The journalists have handled them with great caution. A story in the German publication Der Spiegal, co-bylined by Poitras, claims the documents include information "that could endanger the lives of NSA workers," and an Associated Press interview with Greenwald this last weekend asserts that they include blueprints for the NSA's surveillance systems that "would allow somebody who read them to know exactly how the NSA does what it does, which would in turn allow them to evade that surveillance or replicate it."

But Snowden also reportedly passed encrypted copies of his cache to a number of third parties who have a non-journalistic mission: If Snowden should suffer a mysterious, fatal accident, these parties will find themselves in possession of the decryption key, and they can publish the documents to the world.

"The U.S. government should be on its knees every day begging that nothing happen to Snowden," Greenwald said in a recent interview with the Argentinean paper La Nacion, that was highlighted in a much-circulated Reuters story, "because if something does happen to him, all the information will be revealed and it could be its worst nightmare."

It's not clear if Snowden passed all of the documents to these third parties or just some of them, since Greenwald says Snowden made it clear that he doesn't want the NSA blueprints published.

Either way, Snowden's strategy has been described jocularly in the press as a "dead man's switch" – a tactic popularized in movies and thrillers whereby a bomber or criminal mastermind has a detonator wired to a bomb and the only thing keeping it from exploding is his finger on the detonator button. If police shoot him, he releases the button and the bomb goes off.

But Snowden's case is actually a kind of reverse dead man's switch, says John Prados, senior research fellow for the National Security Archive and author of several books on secret wars of the CIA.

"As an information strategy, what Snowden is doing is similar to that, but it doesn't have the same kind of implication," Prados says. "We're not setting off a bomb or having some other kind of weapon-of-mass-destruction go off."

In the popular scenarios, the person has control over the event, and the weapon or deadly force is liberated or detonated only if that person is neutralized in some way and control is taken away from him. But the element of control is much different in Snowden's case.

"In the dead man switch, my positive control is necessary in order to prevent the eventuality [of an explosion]," Prados said. "In Snowden's information strategy, he distributed sets of the information in such a fashion that if he is taken, then other people will move to release information. In other words, his positive control of the system is not required to make the eventuality happen. In fact, it's his negative control that applies.

"The operation of the system is reversed. He's not calling up someone every 25 hours saying I'm still free, don't let the stuff out. The stuff is out, and if he isn't free, then they let it out. The dynamic is reversed from the traditional concept of the dead man switch."

Greenwald told the Associated Press that media descriptions of Snowden's tactic have been over-simplified.

"It's not just a matter of, if he dies, things get released, it's more nuanced than that," he 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."

The classic application of a dead man's switch in the real world involves nuclear warfare in which one nation tries to deter adversaries from attacking by indicating that if the government command authority is taken out, nuclear forces would launch automatically.

It has long been believed that Russia established such a system for its nuclear forces in the mid-60s. Prados says that under the Eisenhower administration, the U.S. also pre-delegated authority to the North American Aerospace Defense Command (NORAD), the Far East command and the Missile Defense Command to use nuclear weapons if the national command authority were taken out, though the process was not automatic. These authorities would have permission to deploy the weapons, but would have to make critical decisions about whether that was the best strategy at the time.

Snowden's case is not the first time this scenario has been used for information distribution instead of weapons. In 2010, Wikileaks published an encrypted "insurance file" on its web site in the wake of strong U.S. government statements condemning the group's publication of 77,000 Afghan War documents that had been leaked to it by former Army intelligence analyst Bradley Manning.

The huge file, posted on the Afghan War page at the WikiLeaks site, was 1.4 GB and was encrypted with AES256. The file was also posted on torrent download sites.

It’s not known what the file contains but it was presumed to contain the balance of documents and data that Manning had leaked to the group before he was arrested in 2010 and that still had not been published at the time. This included a different war log cache that contained 500,000 events from the Iraq War between 2004 and 2009, a video showing a deadly 2009 U.S. firefight near the Garani village in Afghanistan that local authorities said killed 100 civilians, most of them children, as well as 260,000 U.S. State Department cables.

WikiLeaks has never disclosed the contents of the insurance file, though most of the outstanding documents from Manning have since been published by the group.