When Facebook was pilloried for allowing fake news to flourish last November, founder Mark Zuckerberg reacted dismissively: "Of all the content on Facebook," he wrote, "more than 99 percent of what people see is authentic. Only a very small amount is fake news and hoaxes."

Five months later — and with the topic still widely debated — the company has completely changed its tune.

In a keynote speech at the International Journalism Festival in Perugia (IJF) Friday, Adam Mosseri — vice president of product for News Feed at Facebook — highlighted several initiatives the social network was taking to address this problem.

What Zuckerberg initially framed as a trivial issue is being countered with measures aimed at curbing financial incentives for fake news producers, "educational" messages to help users spot fakes and a (soon to be paid) collaboration with third-party fact-checkers to better identify and demote hoaxes on News Feed.

It is not clear if any of this is actually working. More than three months into the fact-checking effort, the company has not shared any data and claims not to have a precise gauge for it either.

"We’ve seen overall that false news has decreased on Facebook,"  Mosseri said.

"But it’s hard for us to measure," he added, "because we can’t read everything that gets posted."

In contrast with Zuckerberg's "99 percent" claim, Mosseri remained extremely vague on the degree of authenticity of content shared on the platform.

He was also quick to stress that he couldn't rule out that any reduction in circulation of what the company now labels "false" — not "fake" — news can be attributed to its combined efforts rather than contextual factors.

"I don’t want to jump to any conclusions," said Mosseri, "because that might be due to some of our efforts but it also might be to do with the fact that we’re post-election cycle in the U.S. right now."

Mosseri did confirm that Facebook is looking to further internationalize the fact-checking program currently involving three European countries and the U.S. "as quickly as we can," and that there was more work left to do.

"I don't want to assume we've done enough," Mosseri said in response to a question. "I think we have got a lot more to do."

Mosseri did not commit to releasing data from the fact-checking program to the public during his talk.

Facebook has repeatedly made clear its intention not to become an arbiter of truth while emphasizing its intention to establish a better partnership with the news industry.

During his speech, Mosseri acknowledged that "we haven’t always been the best at communicating."

The Facebook executive's lack of specificity reminded some IJF old-timers of another missed opportunity to bring clarity to Facebook’s motives and operations.

Two years ago, Facebook’s Director of News and Media Partnerships Andy Mitchell argued that users — not Facebook — control News Feed. At the time, this self-absolution left NYU Professor of Journalism Jay Rosen completely unsatisfied, and now looks patently at odds with the concern expressed over fake news.

Mosseri was clear, however, that "false" news is now an important issue for Facebook. This is not just because of the fines threatened by legislation like the one just approved by Angela Merkel’s cabinet in Germany.

"We don’t want false news on our platform,"  Mosseri said, because "it’s bad for people, it’s at odds with our mission and it’s bad for our business. Eroding trust in Facebook over the long run is going to be really bad for us as an advertising business."