Since Mr. Trump took office, more than 40 foreign governments have invoked the specter of “fake news” to discredit journalists in the United States and abroad.

Reports by @CNN that I will be working on The Apprentice during my Presidency even part time are ridiculous & untrue - FAKE NEWS!

“Concocting fake news to attract eyeballs is a habitual trick of America’s New York Times, and this newspaper suffered a crisis of credibility for its fakery,” the Chinese government declared after The Times broke the news this month of government documents detailing the internment of Uighurs, Kazaks and other Muslims in the northwestern region of Xinjiang.

Who would have guessed that history had such a perverse development in store for us? As the historian Timothy Snyder has written in The Times, Adolf Hitler and the Nazis came up with the slogan “Lügenpresse” — translated as “lying press” — in order to discredit independent journalism. Now the tactic has been laundered through an American president, Donald Trump, who adopted the term “fake news” as a candidate and has used it hundreds of times in office.

That is how, barely a generation after the murder of millions of Jews in Nazi death camps, the term “fake news” has come to be deployed so brazenly by another repressive regime to act against another minority, to cover up the existence of prison camps for hundreds of thousands of Muslims.

Mr. Trump surely didn’t intend this. He’s not a strategic or particularly ideological person. He tends to act instead out of personal or political interest and often on impulse, based on what he thinks his core supporters in the country or the cable television studios want from him. When he yanks troops out of Syria or pardons war criminals, it’s safe to assume he’s not thinking about the long-term balance of power in the Middle East or the reputation and morale of the American military. He is maneuvering, as ever, for some perceived immediate political advantage.

So it is with his attacks on the news media. Mr. Trump loves the press. He has catered to it and been nurtured by it since he first began inventing himself as a celebrity in the 1970s. But he has needed a way to explain to his followers why there are so many upsetting revelations about incompetent administration officials, broken campaign promises and Trump family self-dealing. He’s now tweeted out the term “fake news” more than 600 times.

Playing the ‘Fake News’ Card Since December 2016, President Trump has tweeted about “fake news” at least once a month. Other countries have followed suit. “Fake news” tweets by month Impeachment inquiry announced 40 Twelve Russian intelligence operatives indicted 30 20 10 0 2017 2018 2019 Countries citing “fake news” Impeachment inquiry announced “Fake news” tweets by month 40 30 Twelve Russian intelligence operatives indicted 20 10 0 2017 2018 2019 Countries citing “fake news” Source: Trump Twitter Archive, news reports

When an American president attacks the independent press, despots rush to imitate his example. Dozens of officials around the world — including leaders of other democracies — have used the term since Mr. Trump legitimized it. Why bother to contend with facts when you can instead just pretend they don’t exist? That’s what the Chinese government did. It simply called the Times report fake, though it was based on the government’s own documents, and declared it “unworthy of refutation.”

Following the same Oval Office script, a senior government official in Burundi trotted out “fake news” to explain why his government was banning the BBC. In Myanmar, where the government is systematically persecuting an ethnic minority, the Rohingya, an official told The Times that the very existence of such a group is “fake news.” The Russian foreign ministry uses the image of a big red “FAKE” stamp on its website to mark news reports that it does not like.

Jordan has introduced a law allowing the government to punish those who publish “false news.” Cameroon has actually jailed journalists for publishing “fake news.” Chad banned social media access nationwide for more than a year, citing “fake news.”

As Shepard Smith, a former Fox News anchor, recently told attendees at the annual dinner of the Committee to Protect Journalists, “Intimidation and vilification of the press is now a global phenomenon. We don’t have to look far for evidence of that.”

The press needs to be scrutinized. Its mistakes should be called out, its biases analyzed and exposed. But Mr. Trump has licensed a far more dangerous approach.

The rise of the epithet “fake news” as a weapon is occurring at an already perilous moment for the supply of information about the world as it truly is. The financial foundations of an independent press are eroding under the influence of the internet, which has simultaneously become a global conduit for malicious falsehoods. It’s harder and harder for anyone to know what stories to believe. A world in which governments and citizens can’t agree on a shared set of facts is one in which only the most powerful thrive.

The health of democracy, in the United States and around the world, depends on better answers to this challenge. Rather than making matters worse, politicians should be pursuing those answers, for example by pressing leading internet companies to accept responsibility for the roles they have already assumed as the world’s leading information publishers. The press has to do its part as well, by committing itself to a forthright accounting of any mistakes, an unending struggle against bias in news and an uncompromising pursuit of truth.

Some American politicians, from Maine to Alabama, have followed Mr. Trump’s example. But others have been wise enough to dissent, however cautiously. Senator Mitch McConnell of Kentucky, the majority leader, offered a rare if tepid defense of the media in August 2017. “My view is that most news is not fake,” he told a Louisville audience.

This month, Mr. McConnell went to the Senate floor to highlight The Times’s reporting on Xinjiang, describing the documents published by The Times as “a handbook for this Orwellian campaign to effectively erase a religious and ethnic minority in a region that is supposed to be legally distinct from the rest of China.”

The capacity of news organizations to produce this kind of journalism — and to reach an audience that will listen — is contingent and fragile. Mr. Trump shows no sign of seeing this bigger picture, or, perhaps, of caring about it. So it falls to the rest of us, particularly leaders like Mr. McConnell, to tell the truth about a free press, to proclaim its value, in the United States and around the world.