For decades, journalists have received and published government secrets in the public interest with the protection of the First Amendment.

Think of the Pentagon Papers, which told Americans about their government’s hidden (and often unsavory or illegal) behavior during the Vietnam War. The New York Times and The Washington Post received the highly classified information from a former Pentagon official, Daniel Ellsberg, and – though legal battles raged – were able to publish them.

Or think of The Post’s reporting (along with that of the Guardian) that exposed the National Security Agency’s massive global surveillance programs, with much the information supplied by the former government contractor Edward Snowden.

Or, years earlier, the Times reporting about how the government was secretly monitoring the calls and emails of people inside the United States without court-approved warrants.

All won Pulitzer Prizes, and all informed citizens about activities their secrecy-obsessed government didn’t want them to know.

That kind of reporting – perhaps the most important journalism there is – may have become an endangered species Thursday with a new indictment of WikiLeaks co-founder Julian Assange under the Espionage Act.

For good reason, press-rights advocates are far more alarmed now than they were last month when Assange was initially indicted.

“This is unlike anything we’ve seen before, and it crosses a bright red line for journalists,” said James Risen, a longtime national security reporter for the Times and now director of the First Look Press Defense Fund. While a Times reporter, Risen (co-author of the warrantless wiretapping story) struggled for years to avoid testifying about his confidential source during the leak investigation of Jeffrey Sterling, a former CIA officer.

The expanded indictment goes after Assange for his role in obtaining and publishing secret military and diplomatic documents in 2010.

What’s alarming about the indictment is the way it would criminalize some of the basic functions of newsgathering and publication.

“The message of this indictment is that national security journalism is possibly criminal,” said Jameel Jaffer, director of the Knight First Amendment Institute at Columbia University.

And no matter what happens with the case, he said, “it’s hard to see how that message won’t change how news organizations operate.” That is very much the intended message, he said.

And, in turn, that chilling effect would deprive the public of information it should know. Using examples from the recent past, Jaffer mentioned the long-secret American drone program and the abuse and torture of prisoners at the CIA’s so-called black sites.

If whistleblowers are afraid to leak information and if news organizations fear receiving and publishing it, citizens will know only what the government wants them to know, through what he sardonically called “executive grace.”

In other words, the architects of secret, and possibly illegal or immoral, government programs would be the same people who get to decide whether information about them is made public.

Underlying all of this is the monumental overclassification of government information that drastically increased after 9/11 – a system that’s almost universally acknowledged to be badly broken.

That means that journalists and citizens are caught in a tighter-than-ever squeeze: Far too much that they should know has been labeled secret, and the accepted ways of informing the public are at risk of being criminalized.

The Trump administration’s aggressive antipathy toward journalists is an undeniable element, too.

“The administration has gone from denigrating journalists as ‘enemies of the people’ to now criminalizing common practices in journalism that have long served the public interest,” Post Executive Editor Martin Baron said in a statement.

Or as Risen put it: “It’s very obvious that the White House and Trump are pressuring and politicizing the Justice Department to go after the press.”

Julian Assange is such a divisive, even hated figure, that a straw-man argument often crops up when he is threatened with prosecution.

Assange isn’t really a journalist, goes this thinking, so journalists and others who care about press rights shouldn’t be worried about what happens to him.

In this case, nothing could be further from the truth.

Assange may be an easier target because he is such a lightning rod – and, for some, because of his role in publicizing Democratic National Committee emails that damaged Hillary Clinton’s 2016 campaign against Trump.

The ever-more-political Justice Department – and the press-baiting president – are no doubt well aware of his vulnerability.

But that is very far off the main point.

No one should diminish the danger or the importance of this despicable indictment because they don’t approve of Assange.

Margaret Sullivan is The Washington Post’s media columnist. Previously, she was the New York Times public editor, and the chief editor of the Buffalo News, her hometown paper.