For months, defenders of America's spy agencies have been touting a classified Pentagon report as proof that Edward Snowden's unprecedented disclosures have grievously harmed intelligence operations and placed American lives at risk. But heavily redacted excerpts of that report, obtained by the Guardian under a Freedom of Information Act request and published on Thursday, suggest that those harms may be largely hypothetical – an attempt to scare spy-loving legislators with the phantoms of lost capability.

The first thing to note is that the Pentagon report does not concern the putative harm of disclosures about the National Security Agency programs that have been the focus of almost all Snowden-inspired stories published to date. Rather, the Defense Intelligence Agency's damage assessment deals only with the potential impact of "non-NSA Defense material" that the government believes Snowden may have obtained. Any harm resulting from the disclosure of NSA-related material – in other words, almost everything actually made public thus far – is not included in this assessment.

In fact, the unredacted portions of the report don't discuss published material at all. Instead, the Pentagon was assessing the significance of the information "compromised" by Snowden – all the documents they believe he copied, whether or not they ever see the light of day.

It certainly makes sense for the government to try to gauge the harm that could result if all that information was disclosed, but that's very different from saying harm has occurred. There is always the risk that a hostile government could somehow gain access to the Snowden cache, but the journalists with access to that trove say Snowden himself has insisted that they exercise discretion, publishing only material whose disclosure is in the public interest.

Even that estimate of possible harm, however, is almost certainly overblown. Astonishingly, the government still appears not to have any idea how much information Snowden copied. Intelligence officials estimate that he accessed some 1.7m documents, and are operating on the assumption that he took every document he had access to. Yet there's no reason to believe that assumption is true, and journalist Glenn Greenwald – one of the few with full access to the Snowden trove – has consistently described it as containing "tens of thousands" of documents, not millions.

The almost complete lack of details in the redacted report make it difficult to evaluate it with confidence, but the Pentagon's assessment that the compromised information "will have a GRAVE impact on U.S. national defense" may reflect little more than the government's own unrealistic definitions. After all, by executive order, documents are supposed to be classified as "top secret" only if they "reasonably could be expected to cause exceptionally grave damage to national security". Snowden obviously copied many documents classified as top secret – so they can be expected to cause exceptionally grave damage, by definition.

Except, of course, that's not automatically true. But don't take my word for it: just ask former Director of National Intelligence Dennis Blair, who in 2009 acknowledged that "there is a great deal of over-classification" in government. "Some of it, I think, is done for the wrong reasons, to try to hide things from the light of day," Blair explained. "Some of it is because in our system, there is no incentive not to do that, and there are penalties to do the reverse, in case you get something wrong and don't classify it."

In this, Blair echoed the findings of a formal intelligence community review, which concluded that terms like "grave damage" were not used in any clear or consistent way across the community. As a result, documents are routinely classified without any explanation of how or why their disclosure would be harmful. Current DNI James Clapper has even said that the government should have voluntarily revealed the most notorious program leaked by Snowden: the NSA's vast database of telephone records. Presumably Clapper was not suggesting that the government should have voluntarily inflicted grave harm on national security.

In short: the Pentagon damage report concludes that the "staggering" cache of documents that Snowden might have taken (most of which he probably didn't) could potentially cause grave harm if disclosed to a foreign power (which, as far as we know, they haven't been), and assumed that only genuinely super-sensitive information gets classified (which top intelligence officials concede isn't true).



If this be treason, then the bar has fallen awfully low these days. But we can rest assured that Edward Snowden's critics will make the most of it all the same – anything to distract from the grave impact NSA has already had on global privacy.