The U.S. official, who works regularly with these sites, said the defense community had already been fighting the natural inclination of those in the closed field of intelligence to restrict more of the portals by requiring passwords, even before the WikiLeaks incident.
Out on the battlefield, the WikiLeaks episode may also cause a new reluctance to share information. From a sergeant on the ground writing an after-action report following combat, to a supervisor reading the documents, there could well be a new push to leave information out rather than risk having it leaked.
That could make it harder for military headquarters to get an immediate assessment of what's really happening on the battlefield, some officials say. And it could harm the ability of military historians later to make sense of the war.
But there's pressure from the other direction as well: No intelligence manager would want to be responsible for holding back information that could connect the dots and prevent a terrorist attack.
Steven Aftergood, a specialist on government secrecy at the Federation of American Scientists, predicted that agencies would look for ways to tag records through electronic watermarks, so that their origins, and the leaker, could be more easily identified.
Former CIA chief Hayden, who now works at the Chertoff Group, a Washington-based consulting firm, went further, suggesting pouring resources into "real-time keystroke analysis of government employees," monitoring everything they type and creating a perpetual cyber-polygraph.
While that already happens at some top-secret facilities, expanding the effort to the hundreds of thousands of people who access the SIPRNet could add millions of dollars to the nation's already-huge costs of fighting terrorism and two wars.