"Before people were told that anything they did on their government computer was fair game. You did not have 'reasonable expectation of privacy'. If you wanted to be safe [from prying eyes] you had to log on to your private account. Now the Government is saying they will look at private emails, texts and phone calls, using souped-up software. That will escalate the war on whistleblowers by an order of magnitude."
Trevor Timm, executive director of the Freedom of the Press Foundation, sees the inquiry as a "wide-ranging fishing expedition" that targets senior officials in a bid to starve reporters of information on what the Government is up to even though "talking to reporters is not a crime".
The war on whistleblowers is also a war on journalists and, more broadly, a war on the public's right to know what government does in their name.
"There's basically this massive national security state that is unaccountable to the American people," says Timm. "Without oversight by the Government, the only way to report wrongs is to go to the media."
The FBI hunt takes place as a grand jury continues its investigation into WikiLeaks, creating a climate where reporters who talk to officials about classified material risk prosecution. Despite New York Times executive editor Jill Abramson saying that "no story about details of government secrets has come near to demonstrably hurting the national security in decades and decades", the Administration has subpoenaed reporter James Risen three times in a bid to make him admit that former CIA officer Jeffrey Sterling was his source on a story about a CIA operation to delay Iran's nuclear programme that backfired.
Another Department of Justice probe is hunting who alerted the Associated Press to a CIA operation in the Yemen that allegedly foiled an al-Qaeda plot to bomb an airliner last year. An anonymous source told the Post the inquiries had a "chilling effect" with officials "less open to talking to reporters".
At the same time, all personal data uploaded by the internet and stored in the "cloud" can be accessed by US intelligence agencies without a warrant, using the Foreign Intelligence Surveillance Act. The department's national security division chief, Lisa Monaco, says prosecuting leakers who do "tremendous damage" is a priority.
But Radack, formerly an ethics adviser for the department, believes the Stuxnet inquiry has chilling implications for media freedom. "You would not know your emails are being plundered. The journalist with whom you communicated would not know. But the Government would know. They could convene a grand jury and present that information, all of it occurring in secret without your knowledge.
"It's a very overused and abused term that our Government can attach to pretty much anything and everything," says Radack, adding it had been used to camouflage the biggest scandals of the Bush era: warrantless wiretapping of Americans, "extraordinary rendition" or kidnapping, and torture.
Leaks also exposed the Abu Ghraib prison abuses, the CIA's secret "black sites" to hide detainees and the illegal targeting by drone strikes of US citizens linked to terrorism.
"Like all the Obama leak prosecutions none of these revelations resulted in any tangible harm," says Glenn Greenwald on OpEdNews, "yet all revealed vital information about what our Government was doing in secret."
Despite promises to "usher in a new era of open government", the Administration has prosecuted a record six officials using the 1917 Espionage Act.
Last week, former CIA officer John Kiriakou received 30 months in jail for leaking to a reporter the identity of a covert agent.
The agent's name was passed to an investigator working for a lawyer of a Guantanamo detainee.
Kiriakou also helped blow the whistle on waterboarding. While he waits to begin his sentence, the torturers have been granted immunity.
Ironically, the torture debate was reignited by Zero Dark Thirty, Hollywood's take on the Osama bin Laden manhunt and, say critics, an egregious example of politically motivated leaks to burnish the administration's image.
In contrast, Laura Poitras, the Oscar-nominated director of The War on Terror trilogy, has been repeatedly stopped and questioned by US agents. Her third documentary will look at US surveillance and whistleblowers.
The attack on whistleblowers parallels stepped-up efforts to prosecute hackers.
Timm cites Aaron Swartz, the on-line activist who killed himself last month after he was threatened with 35 years' jail and a US$1 million ($1.18 million) fine for posting academic articles, funded with public money, online.
The Stuxnet investigation coincides with a report in the New York Times that the US plans to quintupled the NSA's Cyber Command, from 900 to 4000 staff.
Bush Administration national intelligence director Admiral Michael McConnell said the NSA should be able to identify any and all internet users and their computers and, if considered necessary, retaliate.
