(CNN) -- U.S. intelligence agencies fear Edward Snowden has achieved celebrity as a leaker and could be inspiring others to disclose classified national security information.
One indication of that may be in new documents published this week by the Intercept, the website begun by Glenn Greenwald, who published Snowden's leaks.
Government officials believe the documents, labeled "Secret," came from a Pentagon-run computer network called SIPRnet that government agencies used to share classified information. Investigators are looking for the leak.
Rep. Adam Schiff, a member of the House Intelligence Committee, called it the "copycat phenomenon" and noted it was a big concern.
"The degree that people have been lionizing Snowden, it encourages people to make a name for themselves by leaking," Schiff told CNN in an interview.
Schiff said the issue has come up in intelligence briefings that he couldn't talk about.
"It's a concern we've discussed: That Snowden has become the model for other leakers," he said.
Snowden inspired by others
Snowden has said that he was inspired by others who disclosed secrets, including Daniel Ellsberg, who leaked the Pentagon Papers in 1971.
He also has said that he considered the former Army private, now called Chelsea Manning, a hero. Manning leaked hundreds of thousands of classified documents to the anti-secrecy group WikiLeaks on the wars in Iraq and Afghanistan.
Like Snowden is now by the Obama administration, Ellsberg was demonized at first by the Nixon administration.
Decades later Ellsberg is widely praised for revealing the government's secret dealings in Vietnam and neighboring countries.
Snowden, who has lived in exile in Russia for a year to avoid U.S. criminal charges, has encouraged others to come forward.
In the year since his leaks on U.S. surveillance practices, the Obama administration has tried to improve security at the agencies handling the nation's secrets.
NSA security tightened
The National Security Agency, where Snowden worked as a contractor, has tightened its computer security aiming to ensure no one can carry out a theft of the size of which was attributed to Snowden: 1.7 million documents.
The Director of National Intelligence has issued rules across all related agencies to try to better track contact with the media.
At the same time, the administration is bowing to countervailing pressure to limit how prosecutors pursue leak investigations.
It is now reining-in aggressive tactics, such as declaring journalists co-conspirators with leakers and subpoenaing journalists to reveal sources.
The spate of leak scandals stems in part from the government's move since the September 11, 2001, terror attacks to more broadly share information.
Some of the 9/11 hijackers were being tracked by one or more federal agencies. But the failure to share information across various agencies is one reason why the 9/11 attacks succeeded, officials have said.
Schiff said the lesson learned then was to "break down the silos" of information. That effort, perhaps went too far.
"Beginning with Manning, you see people having access to things they had no reason to access to," Schiff said. "The pendulum is clearly swinging back in the other direction."
Millions get clearances
A recent GAO study concluded the Pentagon approved as many as 3.2 million people for access to secret and higher-level classified information between 2006 and 2011.
Schiff said there were far too many people with security clearances. At the same time, he said the government's national security work requires some secrecy.
Revealing the methods by which security agencies try to prevent terror could show terrorists how to evade detection and thereby increase the risk of a disastrous attack.
Intelligence agencies are "kind of damned if they do and damned if they don't," he said.