Hillary Clinton was about to be indicted, Pope Francis endorsed Donald Trump: the battle over fake news is heating up after a White House campaign in which the misinformation industry may have swung the outcome of the vote.
Last week, Google and Facebook moved to cut off ad revenue to bogus news sites. But media watchers say more is needed to stamp out a powerful phenomenon seen by some people as a threat to democracy itself.
"If everything seems to be the same and no distinctions are made, then we won't know what to protect," Obama said during a visit to Germany.
The hoaxes of the 2016 election season were in many cases spectacular - "Did the Clintons Commit Murder?" - and created by groups purely out to make money from clicks and ads.
And since Trump's victory, reports have exposed the dark underbelly of operations - run from Macedonia to California - that boast of making easy money with wholly fabricated stories, under such headlines as "Look At Sick Thing He Just Did To STAB Trump In The Back."
An analysis published by BuzzFeed News found that the 20 top-performing bogus stories from hoax websites and extremely partisan blogs generated slightly more than 8.7 million "shares" on Facebook to just 7.4 million from major news websites, in the three months before the election.
Now, the outcry over fake news and its apparent role in the election is prompting calls for Facebook to consider itself a media company, with editorial responsibilities, which the social network has repeatedly rejected.
Arbiters of truth?
Washington Post media columnist Margaret Sullivan argued that Facebook "should hire a top-flight executive editor and give that person the resources, power and staff to make sound editorial decisions."
For Gabriel Kahn, a former journalist who teaches at the University of Southern California, "they're in the same business as pretty much every media company, which is aggregating audiences and using that to sell advertisements."
And Kahn believes that Facebook, by considering itself a "neutral" platform, "allows the media ecosystem to be polluted" with bogus news.
"The problems here are complex, both technically and philosophically," Zuckerberg said in a posting.
"We believe in giving people a voice... We do not want to be arbiters of truth ourselves, but instead rely on our community and trusted third parties."
Zuckerberg said nonetheless that Facebook would step up efforts to weed out fake news with "stronger detection," an easier process to report hoaxes and "third party verification" from "respected fact checking organizations."
Tech entrepreneur Elad Gil said it should not be too difficult for a company like Facebook to apply its technical expertise to determine when a news story is fake.
"Intriguingly, a group of undergrads at Princeton were able to build a quick and dirty fake news classifier during a 36-hour hackathon," Gil said in a blog post.
'Click farms' vs ideology
Northeastern University journalism professor Dan Kennedy argued that it is important to differentiate between "click farms" which make money off entirely fake news and politically driven news sites.
"I think Facebook could do a lot to crack down on fake news, and I think that's something everybody could agree on, but if they try to go against the ideologically motivated sites it will inevitably get caught up in the culture wars," Kennedy said.
The prevalence of ersatz news, analysts note, comes in a context of deep distrust of mainstream media, which is often accused of one-sidedness.
Any effort to filter out those voices could "lead to the relitigation of ancient disputes over media bias," said Kennedy.
Reason magazine editor Scott Shackleford said it would be hard to draw a line between filtering bogus news and ideological censorship.
"So a decision by Facebook to censor 'fake news' would heavily weigh in favor of the more mainstream and 'powerful' traditional media outlets," he wrote.
City University of New York journalism professor Jeff Jarvis and startup entrepreneur John Borthwick argued in a blog post that the media and technology industries should work together to help readers establish the credibility of news.
"We do not believe that the platforms should be put in the position of judging what is fake or real, true or false as censors for all," they wrote.
"The platforms need to give users better information and media need to help them."
Even if the online platforms do not turn into media firms, the two wrote in the blog, they should "hire high-level journalists inside their organizations" to "bring a sense of public responsibility to their companies" and "to explain journalism to the technologists and technology to the journalists."