It was last Friday at precisely 9:24 p.m. that the New York Post’s unverified and possibly false story linking Joe Biden to his son Hunter’s unseemly dealings in Ukraine crossed the line from conspiracy theory to fodder for mainstream discourse.

The occasion was a tweet by CBS News reporter Bo Erickson, who announced to his 28,500 followers that he’d asked the former vice president about it — and who, in turn, was none too pleased.

“He called it a ‘smear campaign’ and then went after me,” Erickson wrote, quoting Biden as saying: “I know you’d ask it. I have no response, it’s another smear campaign, right up your alley, those are the questions you always ask.”

Biden does indeed appear angry in the accompanying video. And why shouldn’t he? In fewer than three days, an unsupported allegation based on emails of dubious provenance had slithered up the media food chain from Rupert Murdoch’s sleazy scandal sheet to what we once called the Tiffany Network. Now the story was “Biden denies,” and if — as appears more than possible — it was the work of disinformation agents, then they must have taken great satisfaction in a job well done.

The details of the story hardly matter. Even if the emails are genuine, all they show is that Joe Biden may have met with an official from Burisma, the Ukrainian energy company that paid Hunter Biden to sit on its board. Biden, as vice president, pressured the Ukrainian government to fire the prosecutor who was investigating Burisma. But as this piece by PolitiFact explains, it has long since been established that the prosecutor himself was corrupt, and that Joe Biden was acting on behalf of the U.S. government and the Western alliance.

What does matter is that the Post story has all the earmarks of disinformation from the campaign of President Donald Trump, from Russian interests or from both.

Consider that the two sources were former Trump adviser Steve Bannon and former New York Mayor Rudy Giuliani, one of Trump’s personal lawyers. One of Bannon’s best-known maxims is that “the real opposition is the media. And the way to deal with them is to flood the zone with s**t.” Because, inevitably, the media just can’t resist reporting on it, even it’s to debunk it or, in the case of Erickson, to get the victim to say something about it.

Moreover, The Washington Post reported last week that U.S. intelligence agents had warned months ago that Giuliani was “the target of an influence operation by Russian intelligence,” and that he was passing along Russian disinformation to the president as part of his so-called investigation into the Bidens’ connections with Ukraine. Trump’s reported response: “That’s Rudy.”

Now, I don’t mean to suggest that it was a straight line from the New York Post to CBS News. There have been more than a few zigzags along the way.

For instance, there is the matter of why Giuliani’s latest “drug deal,” to recycle John Bolton’s apt phrase, found its way into the Post rather than a more respectable sector of Rupert Murdoch’s media empire. If the story had been broken by The Wall Street Journal, for instance, we’d all be taking it seriously.

As it turns out, what Giuliani was peddling was too rancid even for Fox News, yet another Murdoch property. According to Mediaite, the news department at Fox rejected Rudy’s pitch because the veracity of the emails — allegedly found on a laptop that Hunter Biden had left at a Delaware repair shop — couldn’t be verified.

Crisis averted? Hardly. That’s not how the media food chain works. Because after the story appeared in the Post, Fox News hosts immediately began talking it up. According to the liberal watchdog group Media Matters for America, the story was discussed more than 100 times between Wednesday and Friday — not just on the opinion shows, but on the news side as well, even though the operation’s actual journalists had taken a pass on it.

And even within the Post, the story proved toxic. The New York Times reported that there were such misgivings in the Post’s newsroom that those involved in writing it refused to have their bylines put on it. In the end, the bylines of two women who may not have had much to do with it were placed atop the story. One, according to the Times’ sources, had “little to do with the reporting and writing of the article” and “learned that her byline was on the story only after it was published.”

The smear led to the usual handwringing at Facebook and Twitter as well. As The Guardian reported, both platforms took steps to limit the reach and distribution of the story on the grounds that the emails had not been verified. And that, in turn, led to the usual complaints from Republicans that the two services were censoring news that had a rightward slant. “Twitter’s censorship of this story is quite hypocritical,” wrote Sen. Ted Cruz, R-Texas, to Twitter chief executive Jack Dorsey, “given its willingness to allow users to share less-well-sourced reporting critical of other candidates.”

As I wrote recently, the media for the most part have been less gullible in covering the presidential campaign than they were four years ago, when Hillary Clinton’s emails were conflated into a massive scandal despite all evidence to the contrary. This time around, for instance, the press treated unproven claims by Tara Reade, a former Senate staffer who charged that Biden sexually assaulted her a generation ago, with the skepticism they deserved.

But Giuliani, in particular, has refused to let go of the Ukraine story. And it’s got to be damaging to Biden on at least some level for it to resurface just a few weeks before the final day of voting. You can be sure it will come up at this Thursday’s debate, and it is exactly the kind of complicated tale that can’t be refuted with a soundbite. The challenge for Biden will be explaining it in simple terms while Trump is interrupting him and yelling at him, regardless of whether his mic has been cut.

A few minutes after Bo Erickson tweeted out Biden’s response, his CBS News colleague Paula Reid came to his defense. “Biden adopts Trump playbook” by “attacking” Erickson, she tweeted, adding: “Fine to attack the story, but why personally insult Bo?”

The “Trump playbook”? Seriously? Biden’s response was sharp and a little rude, but hardly out of line given that Erickson was giving mainstream credibility to an unverified smear. Fortunately for Biden, the media for the most part appear not to be taking it seriously.

But the question of how to handle such unproven and unprovable allegations remains unanswered. Ignore them, and you’ll be accused of bias — and the story will get out there anyway. Debunk them, and you’re giving them wider play. Ask the target about them, and you run the risk of #bothsides-ism.

It’s a miserable dilemma. But that’s the state of media and politics in 2020.

GBH News contributor Dan Kennedy’s blog, Media Nation, is online at dankennedy.net.