Story highlights Michael Hayden: Snowden will likely be most damaging leaker in American history

He says the large trove of data reveals how America collects much of its intelligence

Hayden says U.S. economic rivals will use it to disadvantage American companies

He says other nations will doubt whether the U.S. can do anything in secret

Edward Snowden will likely prove to be the most costly leaker of American secrets in the history of the Republic.

I know that we have had our share of spies.

Benedict Arnold was bent on betraying the garrison at West Point to the British during the Revolution. Klaus Fuchs and Julius and Ethel Rosenberg ferreted out nuclear secrets for the Russians. Aldrich Ames and Robert Hanssen identified American penetrations for ultimate execution by the Soviets.

We have also had our share of leakers.

Daniel Ellsberg copied thousands of pages of documents related to the Vietnam War. Bradley Manning is accused of indiscriminately scoured the Defense Department's SIPRNET (Secret Internet Protocol Router Network) for all manner of military reports and diplomatic cables.

But Snowden is in a class by himself.

Michael Hayden

The secrets that Arnold wanted to betray fit into the heel of the boot of his British case officer. The "atom bomb" spies reported out using secret ink. Ellsberg was limited to the number of documents he could physically Xerox. Manning, although fully empowered by digital media, had access only to a secret level network housing largely tactical information.

Snowden fled to China with several computers' worth of data from NSANET, one of the most highly classified and sensitive networks in American intelligence. The damage is potentially so great that NSA has taken one of its most respected senior operations officers off mission tasks to lead the damage assessment effort.

In general terms, it's already clear Snowden's betrayal hurts in at least three important ways.

First, there is the undeniable operational effect of informing adversaries of American intelligence's tactics, techniques and procedures. Snowden's disclosures go beyond the "what" of a particular secret or source. He is busily revealing the "how" of American collection.

The Guardian newspaper's Glenn Greenwald, far more deserving of the Justice Department's characterization of a co-conspirator than Fox's James Rosen ever was, claims that Snowden has documents that comprise "basically the instruction manual for how the NSA is built. ... [To prove] what he was saying was true, he had to take ... very sensitive, detailed blueprints of how the NSA does what they do."

Greenwald has disputed the notion that he aided Snowden, telling David Gregory on NBC's "Meet the Press": "The assumption in your question, David, is completely without evidence, the idea I've aided and abetted him in any way."

And Michael Clemente, Fox News' executive vice president of news, has said, "we are outraged to learn ... that James Rosen was named a criminal co-conspirator for simply doing his job as a reporter."

Absent "rogue" U.S. action to silence him, Snowden has promised not to reveal this data, but there are already reports of counterterrorism targets changing their communications patterns . And I would lose all respect for China's Ministry of State Security and Russia's FSB if they have not already fully harvested Snowden's digital data trove.

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As former director of CIA, I would claim that the top 20% of American intelligence -- that exquisite insight into an enemy's intentions -- is generally provided by human sources. But as a former director of NSA, I would also suggest that the base 50% to 60% of American intelligence day in and day out is provided by signals intelligence, the kinds of intercepted communications that Snowden has so blithely put at risk.

But there is other damage, such as the undeniable economic punishment that will be inflicted on American businesses for simply complying with American law.

Others, most notably in Europe, will rend their garments in faux shock and outrage that these firms have done this, all the while ignoring that these very same companies, along with their European counterparts, behave the same way when confronted with the lawful demands of European states.

The real purpose of those complaints is competitive economic advantage, putting added burdens on or even disqualifying American firms competing in Europe for the big data and cloud services that are at the cutting edge of the global IT industry. Or, in the case of France, to slow negotiations on a trans- Atlantic trade agreement that threatens the privileged position of French agriculture, outrage more based on protecting the production of cheese than preventing any alleged violation of privacy.

The third great harm of Snowden's efforts to date is the erosion of confidence in the ability of the United States to do anything discreetly or keep anything secret.

Manning's torrent of disclosures certainly caused great harm, but there was at least the plausible defense that this was a one-off phenomenon, a regrettable error we're aggressively correcting.

Snowden shows that we have fallen short and that the issue may be more systemic rather than isolated. At least that's what I would fear if I were a foreign intelligence chief approached by the Americans to do anything of import.

Snowden seems undeterred by any of these consequences. After all, he believes he is acting for a higher good -- an almost romantic attachment to the merits of absolute transparency -- and he seems indifferent to the legitimacy of any claims of national security.

The appropriate balance between liberty and security has bedeviled free peoples, including Americans, for centuries. But it takes a special kind of arrogance for this young man to believe that his moral judgment on the dilemma suddenly trumps that of two (incredibly different) presidents, both houses of the U.S. Congress, both political parties, the U.S. court system and more than 30,000 of his co-workers.

Arrogant or not, Snowden has thrust into public view sensitive and controversial espionage activities. So what of his facts, fictions and fears and of the national debate that he claims he intended to stimulate?

More on this in following columns.