FILE - In this May 1, 2019, file photo, WikiLeaks founder Julian Assange puts his fist up as he is taken from court in London. The Justice Department has charged Assange with receiving and publishing classified information. The charges are contained in a new, 18-count indictment announced May 23, 2019. (AP Photo/Matt Dunham, File)

WASHINGTON (AP) — 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.

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 protected under the law, though they declined to discuss the policy discussions that led to the indictment.

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