Even before the White House press corps was born—in 1896, when newspapers assigned reporters to a table outside the office of Grover Cleveland’s secretary—attentive reporters irritated occupants of the White House. To hide the fact that he had a tumor, Cleveland, in 1893, disappeared from Washington for four days to have surgery aboard a friend’s yacht. In 1913, Woodrow Wilson, who hated the press’s fascination with his three daughters, accused “certain evening newspapers” of quoting him on things he meant to stay off the record. He eventually all but abandoned news conferences. It was six years before Warren G. Harding, who had been a newspaper publisher, revived the tradition.

And, yet, over the years, almost every President has adopted a fruitful, if tense, mutual dependence with the press. Each needs something from the other, and both sides know it. Bruce Catton, a correspondent in the nineteen-forties, defined the constant business of leaking as information that officials were “either unwilling or unready” to reveal by name. Anonymity, ritually bemoaned and practiced by both sides, endures because it allows members of government, high and low, to speak more freely. Earlier this month, anonymity allowed the Washington Post to report, on the basis of nine sources, that Michael Flynn, the national-security adviser, had discussed Obama Administration sanctions with the Russian ambassador before Donald Trump took office, contrary to what Flynn told his colleagues. (Three days later, Flynn resigned.) Early Friday, CNN cited unnamed officials to report that the F.B.I. had rejected a White House request to dispute media reports that Trump’s campaign advisers were frequently in touch with Russian intelligence agents.

Anonymity, of course, is also a tool of the White House. On Thursday, one of Trump’s advisers e-mailed me a statement that began with the words “A WH official confirmed.” In Washington, anonymity, as Winston Churchill said of democracy, is a lousy solution, except for all the others.

But under Donald Trump, the dynamic between the press and the President has turned toxic. As a real-estate developer, Trump was, for many years, an energetic anonymous source (even pretending to be his own P.R. man to salt the local papers with news about himself), but Trump has bridled against the scrutiny applied to every President since Cleveland. On Friday morning, about an hour after his press secretary, Sean Spicer, and chief of staff, Reince Priebus, held an anonymous briefing for the press, Trump publicly excoriated the press’s use of anonymity. In a speech at the Conservative Political Action Conference, he said, “I called the fake news ‘the enemy of the people’—and they are. They are the enemy of the people. Because they have no sources, they just make them up when there are none.” At one point, he posed changes that would effectively alter the First Amendment, saying, “They shouldn’t be allowed to use sources unless they use somebody’s name.” He added, “We’re going to do something about it.”

And do something they did. Shortly after Trump’s speech, his press office narrowed the day’s briefing to what’s known as a “gaggle”—a smaller, off-camera format that is useful for impromptu or informal updates. It turned away CNN, the Times, BuzzFeed, Politico, and other outlets that have published tough stories about his Administration lately. It ushered in Breitbart, the Washington Times, and a conservative outlet called One America Network. When Zeke Miller, of Time magazine, and Julie Pace, of the Associated Press—both of whom are on the board of the White House Correspondents Association—realized that organizations were being excluded, they left in protest. Reporters who stayed later shared the contents of the briefing in full.

The White House defended its actions by saying that every White House holds handpicked, off-the-record sessions, but reporters noted that this was an on-the-record briefing. “In the six years I’ve been here, I’ve never been a party to a gaggle that was not on Air Force One or on the road,” Mark Landler, a senior White House correspondent at the Times, told me. “Handpicking the participants is totally new.”

By day’s end, news organizations still couldn’t decipher whether the change was temporary—a kind of press-office panic attack—or a more permanent turn. Davan Maharaj, the editor-in-chief and publisher of the Los Angeles Times, which was among the excluded, told me, “We don’t know what this means. We don’t know if Spicer is under pressure to show that he’s being tougher with the press. We don’t know if this is another effort at manipulation to shift the topic from whether the Administration inappropriately tried to influence the F.B.I. on the Russian investigation. What it does seem like is another effort to target the press as the disloyal opposition and an attack on what objective truth is.”

There was, of course, no shortage of reasons for the White House to shift the topic. In addition to contacting the F.B.I., according to the Washington Post, the White House also “enlisted senior members of the intelligence community and Congress in efforts to counter news stories about Trump associates’ ties to Russia”—a development that drew comparisons to Richard Nixon’s attempts to stifle the Watergate investigation. In another blow, the White House was confronting an article in the Forward, headlined, “Senior Trump Aide Forged Key Ties to Anti-Semitic Groups in Hungary,” which focussed on Sebastian Gorka, a deputy assistant to the President, who rose through the far-right edge of Hungarian politics.

“I think there are two things going on,” Maharaj said. “I think there is a clear effort to bring the press to heel, something that’s not going to happen to the people who are the purveyors of high-quality journalism in the press in the United States. There’s also a clear effort to delegitimize credible sources of information so when something happens, when we or the New York Times or the Wall Street Journal or the Washington Post pop a story, that there’s a record of already discrediting the source.”

So far, news organizations have been galvanized by the pressure. The Washington Post has added a new motto to its front page: “Democracy Dies in Darkness.” And the L.A. Times has printed up T-shirts, for staff and the public, with the phrase “We will not shut up” in thirteen languages. “Look, we all joined this business to hold officials accountable and to search for truth and to be vigorous in that search,” Maharaj said.

In the days to come, there will be questions to settle. Will the White House Correspondents Association, which said it was “protesting strongly” the exclusions, urge members to boycott the briefings? (For its part, The New Yorker will not attend White House briefings until the exclusions are ended, according to David Remnick, the editor of the magazine.) Will members of Congress see it as another sign of the President’s authoritarian turn? In a telling sign of displeasure, Representative Darrell Issa, the California Republican who had supported Trump in the campaign, called, on Friday, for a special prosecutor to manage the investigation into contacts between Trump associates and Russia.

The course of events will be shaped, above all, by the President himself. Barring a critical press is a step that Trump’s predecessors avoided even at the depths of scandal. During Watergate, Iran-Contra, and the Monica Lewinsky affair, they continued to engage the press because an open society is at the heart of the values that compelled them to seek the White House in the first place. As Spicer himself said in December, the Trump Administration never planned to ban a news outlet: “Conservative, liberal, or otherwise, I think that’s what makes a democracy a democracy versus a dictatorship.”

Every President is tempted, at times, to cower, to bully, to flee—even to a friend’s yacht. For Trump, there is an added incentive. He has at his disposal, and is using to full effect, something previous Presidents didn’t have: social media and a direct method of communication that bypasses the press.

But, historically, most Presidents eventually calculate that it is a ruinous strategy that only intensifies an Administration’s isolation and deepens the public’s distrust. During Grover Cleveland’s first Presidential campaign, in 1884, news broke that he had fathered an illegitimate child. He told his political aides and allies, “Whatever you do, tell the truth.” It contributed to his reputation and ultimately helped him win the White House. But in Washington today, the White House has slipped into a fragile, frantic mode, lurching from crisis to crisis, and not yet able to demonstrate whether its animating value is the preservation of its personnel or its integrity.