WASHINGTON — In a case with significant First Amendment implications, the U.S. filed new charges Thursday against WikiLeaks founder Julian Assange, accusing him of violating the Espionage Act by publishing secret documents containing the names of confidential military and diplomatic sources.

The Justice Department’s 18-count superseding indictment alleges that Assange directed former Army intelligence analyst Chelsea Manning in one of the largest compromises of classified information in U.S. history. It says the WikiLeaks founder, currently in custody in London, damaged national security by publishing documents that harmed the U.S. and its allies and aided its adversaries.

The case comes amid a Justice Department crackdown on national security leaks and raised immediate fear among news media advocates that Assange's actions — including soliciting and publishing classified information — are indistinguishable from what traditional journalists do on a daily basis. Those same concerns led the Obama administration Justice Department to balk at bringing charges for similar conduct.

In this May 16, 2019, file photo. former Army intelligence analyst Chelsea Manning speaks with reporters, outside federal court in Alexandria, Va. (Cliff Owen/AP)

Assange's lawyer, Barry Pollack, said Thursday that the "unprecedented charges" against his client imperil "all journalists in their endeavor to inform the public about actions that have been taken by the U.S. government." The Reporters Committee for Freedom of the Press called the case a "dire threat" to media freedom, and the American Civil Liberties Union said it was the first time in history a publisher was charged for disclosing truthful information.

But Justice Department officials sought to make clear that they believed Assange's actions weren't those of a journalist, though they declined to discuss the policy discussions that led to the indictment.

"Julian Assange is no journalist," said Assistant Attorney General John Demers, the Justice Department's top national security official. "No responsible actor — journalist or otherwise — would purposely publish the names of individuals he or she knew to be confidential human sources in war zones, exposing them to the gravest of dangers."

Zachary Terwilliger, the U.S. Attorney in Alexandria, Virginia, where the case was brought, said Assange was charged with illegally soliciting classified information and not simply publishing it. He said that though the indictment alleges that he published hundreds of thousands of documents, it charges him with disclosing only a "narrow set of documents" related to the identities of confidential sources.

× Fear of missing out? Sign up for the Early Bird Brief - a daily roundup of military and defense news stories from around the globe. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

"The indictment alleges that Assange knew that his publication of these sources endangered them," he said.

Chelsea Manning sent back to jail for refusing to testify in Wikileaks investigation Former Army intelligence analyst Chelsea Manning was ordered back to jail Thursday for refusing to testify to a grand jury, even after telling a judge she’d rather “starve to death” than cooperate with prosecutors.

Prosecutors sought throughout the document to make a distinction between what Assange did as the founder and "public face" of WikiLeaks and the work of journalists.

They noted, for example, that he promoted his site to a convention of European hackers and published a list of the classified information he sought as "The Most Wanted Leaks of 2009." They described how Assange worked with Manning to improperly access Defense Department computers to gain access to thousands of pages of material and encouraged her as she delved through databases for information.

Prosecutors also say the danger wasn't just to the U.S. government, but to people who worked with it.

Reports from the wars in Afghanistan and Iraq published by Assange included the names of Afghans and Iraqis who provided information to American and coalition forces, while the diplomatic cables he released exposed journalists, religious leaders, human rights advocates and dissidents in repressive countries.

Assange said in an August 2010 interview that it was "regrettable" that sources disclosed by WikiLeaks could be harmed, according to the indictment.

Later, after a State Department legal adviser informed him of the risk to "countless innocent individuals" compromised by the leaks, Assange said he would work with mainstream news organizations to redact the names of individuals. WikiLeaks did hide some names but then published 250,000 cables a year later without hiding the identities of people named in the papers.

WikiLeaks played a central role in special counsel Robert Mueller's investigation into possible coordination between the Trump campaign and Russia, having published Democratic emails that were hacked by Russian intelligence officers. The allegations in Thursday's indictment are entirely separate from that episode.

The new Espionage Act charges go far beyond an initial indictment against Assange made public last month that accused him of conspiring with Manning to crack a Defense Department computer password.

First Amendment aside, the indictment poses a secondary ethical question for journalists. News organizations around the world widely used the Manning material, which provided previously unavailable information about the Guantanamo Bay detention center, the wars in Iraq and Afghanistan and international diplomacy. Many reporters found the documents that he released inherently newsworthy.

"These unprecedented charges demonstrate the gravity of the threat the criminal prosecution of Julian Assange poses to all journalists in their endeavor to inform the public about actions that have taken by the U.S. government," said Pollack, Assange's lawyer.

Justice Department officials mulled charges for Assange following the documents' 2010 publication, but ultimately decided that it could be hard to justify charging him with actions that more conventional journalists take.

The posture changed in the Trump administration, with former Attorney General Jeff Sessions in 2017 calling Assange's arrest a priority. Attorney General William Barr paused for several seconds at his confirmation hearing when asked if his Justice Department would ever jail journalists, finally saying there were scenarios when he could envision it as a last resort.

A senior Justice Department official, who spoke on condition of anonymity Thursday to discuss the prosecution, said the case had been "looked at by a number of prosecutors" and prosecutors reached the point "where we believed we had assembled the best case that we could."

Assange, 47, is in custody in London after being evicted from the Ecuadorian Embassy in April. The U.S. is seeking his extradition.

Manning, who was convicted in military court for providing a trove of classified documents to WikiLeaks, is currently in a northern Virginia jail on a civil contempt charge. Manning spent two months in the Alexandria Detention Center beginning in March after she refused to testify to a grand jury investigating WikiLeaks.

Manning has said she believes prosecutors want to question her about the same conduct for which she was convicted at her court-martial. She served seven years of a 35-year military sentence before receiving a commutation from then-President Barack Obama.

Associated Press writers Ben Fox in Washington and Matthew Barakat in Alexandria, Virginia contributed to this report.