By Cokie Roberts and Steven V. Roberts

President Trump has one response to the cascade of news stories connecting his aides and advisers to Russian interests. Instead of rebutting the reports, he attacks the journalists who produce them.

“Many of the leaks coming out of the White House are fabricated lies made up by the #FakeNews media,” he tweeted. “Whenever you see the words ‘sources say’ in the fake news media, and they don’t mention names, it is very possible that those sources don’t exist but are made up by fake news writers. #FakeNews is the enemy!”

Candidate Trump frequently branded the media as the “enemy.” But this is different. This is the president of the United States accusing journalists of fundamental dishonesty, of using sources that “don’t exist” to peddle “fabricated lies.”

He offers no evidence to support his incendiary charges because there is none. The chief source of “fabricated lies” is not the news media. It is the president himself.

Trump’s assaults on the press fit a much larger and deeply dangerous pattern. This president tries to undermine any independent bastion of authority and information — federal judges, FBI investigators, intelligence agencies — that contradict his distorted and deluded view of the world.

And those sources are fighting back, providing the leaks that Trump finds so maddening. “These are not people who pull us aside because they want to screw Donald Trump,” New York Times editor Dean Baquet told CNN. “These are people who are worried about the direction of government.”

“In an administration that has expressed so much distaste for the press and so much distaste for our role, are you surprised that some of the people who want to criticize the administration want to do it without their names attached?” Baquet continued. “I’m not.”

The Times is one of many news organizations taking a particularly aggressive stance toward the Trump administration. One major motivation is the changing nature of the information environment. The president has almost 30 million followers on Twitter. In effect, he controls his own broadcast network that can disseminate his views directly to his supporters without questions or scrutiny from independent journalists.

Another reason: Trump has a well-documented history of using social media platforms to advance his “fabricated lies.” As a result, the press is completely justified in pursuing a policy of relentless skepticism toward the White House.

But with that policy comes real risk. The press must be scrupulously fair as well as skeptical. Steve teaches media ethics at George Washington University, and as he tells his students, one serious ethical pitfall for any journalist comes from wanting a story to be true.

Case in point: During the early days of the Trump presidency, a reporter for Time tweeted that a bust of Martin Luther King Jr., prominently displayed in the Oval Office during the Obama years, had disappeared. The reporter was wrong — the bust had been moved, but not removed — but instead of making sure of his facts, he reached for an explosive exclusive. That kind of self-inflicted wound only validates Trump’s attacks on the media’s credibility.

Another major risk for journalism is the one highlighted by Trump’s tweets: the use of anonymous sources. As the Society of Professional Journalists states: “Anonymous sources are sometimes the only key to unlocking that big story, throwing back the curtain on corruption, fulfilling the journalistic missions of watchdog on the government and informant to the citizens. But sometimes, anonymous sources are the road to the ethical swamp.”

Trump is wildly hypocritical, since he often invokes anonymous sources to support his own shaky allegations, but still, the “ethical swamp” is a real threat. That’s why anonymous sources should be used rarely: only when the story is vital to the public interest and the information cannot be obtained in any other way.

Moreover, all good journalists make sure their sources know what they’re talking about. And they try to describe those informants and say why they should be trusted.

The Washington Post, for example, in a recent account of the feud between Trump and former FBI Director James Comey, explained their story was based on “the private accounts of more than 30 officials at the White House, the Justice department, the FBI and Capitol Hill, as well as Trump confidants and other senior Republicans.”

That’s good journalism. That’s what the public needs to know. That’s why Trump’s accusations are so unfounded. Anonymous sources, used carefully and explained transparently, are vital to the media’s job of holding the president accountable. A healthy democracy depends on them.

Steve and Cokie Roberts can be contacted by email at stevecokie@gmail.com.