WASHINGTON -- The Obama administrations Justice Department has moved beyond investigating and prosecuting leaks at an unprecedented level to claiming in court documents that committing a standard act of journalism may itself be criminal.

In 2010, FBI agent Reginald Reyes described a reporter, recently identified as Fox News ' chief Washington correspondent James Rosen, as possibly being an aider and abettor and/or co-conspirator in the leaking of classified information. Reyes made that argument in his request for a warrant for Rosens personal email account as part of a leak investigation.

The DOJs suggestion that Rosen may be guilty of criminal wrongdoing -- unlike the AP reporters and editors targeted over a May 2012 report about a CIA-thwarted terrorist plot -- is a key difference in the two simmering controversies. The DOJs broad use of subpoena power against the AP, revealed last week , has been widely condemned and seen by many as a threat to press freedom and a means to silence sources, including whistleblowers. The DOJ didn't contact the AP before secretly obtaining two months of journalists' phone records , nor did it contact Fox News before getting Rosen's records, a break with the way the government traditionally deals with media outlets.

But the DOJ is now raising further questions about how far the Obama administration will go in rooting out the sources of classified information.

On Sunday night, the Washington Post reported that the Justice Department had obtained a warrant for Rosens personal email account in rooting out his source for a June 2009 report that North Korea was expected to respond to a U.N. sanction with a nuclear missile test. The alleged source is government adviser Stephen Jin-Woo Kim, who is being charged under the Espionage Act .

The Obama administration has used the World War I-era law, designed to prosecute spies, in six leak-related cases -- more than all previous administrations combined .

From the beginning of their relationship, the Reporter asked, solicited and encouraged Mr. Kim to disclose sensitive United States internal documents and intelligence information about the Foreign Country, Reyes wrote in the search warrant application to obtain Rosens emails. The Reporter did so by employing flattery and playing to Mr. Kims vanity and ego.

Reyes compared Rosens alleged efforts to communicate with Kim through a code to an intelligence officer running a clandestine operation, and alleged that Rosen had returned the favor by providing Kim with news articles in advance of their publication.

What I am interested in, as you might expect, is breaking news ahead of my competitors, Rosen allegedly wrote in an email obtained from one of Kim's accounts that the feds cited as a reason to subpoena all of Rosen's emails.

Kim later allegedly told the FBI that it was the Reporters idea to use covert e-mail communications as a means of compartmentalizing the information and a way for Mr. Kim to feel comfortable talking, according to the FBI search warrant affidavit. I was exploited like a rag doll, he allegedly said.

The unsealed search warrant affidavit from 2010, which does not specifically identify Rosen by name, mentions that Kim and the reporter both worked out of the State Department building. On the day the article was published, according to the FBI investigation, Kim and Rosen departed the State Department building at nearly the same time, were absent for about 25 minutes and returned at around the same time.

FBI investigators determined that Kim and more than 95 other individuals accessed the intelligence report before the publication of the June 2009 article, but that Kim was the only individual who had contact with the reporter on the day of the article's publication.

Internal Justice Department regulations generally require the attorney general to authorize the subpoena of a journalists telephone records, but that rule does not apply to email records. DOJ guidelines would also generally require the attorney general to sign off whenever a journalist is arrested or interrogated, but not when an investigation into their conduct is opened.

Attorney General Eric Holder, who recused himself in the AP case, told NPR last week that he's "not sure" how many times he's authorized the obtaining of journalists' records. Holder declined to comment last week as to whether he recused himself from another ongoing investigation believed to focus on the reporting of New York Times correspondent David Sanger.

A spokesman for the U.S. Attorneys Office for the District of Columbia said in a statement Monday that the office was limited in what it could share because of the ongoing prosecution.

The government exhausted all reasonable non-media alternatives for collecting this evidence before seeking court approval for a search warrant. Based on the investigation and all of the facts known to date, no other individuals, including the reporter, have been charged since Mr. Kim was indicted nearly three years ago, the statement said.

Fox News executive VP Michael Clemente said Monday in a statement that the network is "outraged to learn today that James Rosen was named a criminal co-conspirator for simply doing his job as a reporter."

"In fact, it is downright chilling," Clemente continued. "We will unequivocally defend his right to operate as a member of what up until now has always been a free press.

Glenn Greenwald, a Guardian columnist and former constitutional lawyer, wrote Monday that "it is not illegal to publish classified information" under U.S. law. Greenwald added that because of this, the DOJ appears to now be arguing that "a journalist can be guilty of crimes for 'soliciting' the disclosure of classified information" as a way to "[criminalize] the act of investigative journalism itself."

While Rosen has not been charged, the legal argument that a journalist could be guilty of a crime by obtaining information from a source drew harsh criticism from journalists at outlets that are not typically on the same side of many issues.

The New Yorker's Ryan Lizza tweeted that the "case against Fox's Rosen, in which O admin is criminalizing reporting, makes all of the other 'scandals' look like giant nothing burgers."

Fox News' Brit Hume said Monday that "the Obama-Holder Justice Department is now prepared to treat the ordinary newsgathering activities of reporters -- trying to seek information from government officials -- as a possible crime." Hume, a veteran Washington journalist, said he couldn't "think of a case where that's ever happened before."

Read the search warrant application below:

CORRECTION: This article initially misstated that the AP's May 2012 report was about a thwarted CIA plot, rather than a CIA-thwarted plot.