“I’m really sorry this happened”, Mr Zuckerberg said, and “I’m happy to” appear before Congress “if it’s the right thing to do”.
But the Facebook founder, whose company last year dispatched a top deputy rather than Mr Zuckerberg to testify before Congress on Russian actors seeking to influence the election via Facebook, hedged on the possibility.
“The goal there is to get Congress all the information they need to do their extremely important job and we want to send whoever is best informed”, Mr Zuckerberg said.
He also said Facebook was committed to stopping interference in the US midterm election in November and elections in India and Brazil, adding he was "sure someone's trying" to use the site to meddle.
"There are going to be some new tactics that we need to make sure that we observe and get in front of," he said.
For days Mr Zuckerberg made no public comment on the news that consulting firm Cambridge Analytica, which wielded sophisticated online targeting to shape the 2016 presidential race in the service of Donald Trump’s campaign, had gathered data on some 50 million Facebook users. His absence amid the mounting fallout spurred widespread criticism.
Breaking that silence, Mr Zuckerberg, acknowledged earlier in the day that Facebook had known since 2015 that researcher Aleksandr Kogan shared user data he gathered from an app with Cambridge Analytica.
Both Cambridge Analytica and Mr Kogan certified they had destroyed the information, Mr Zuckerberg said, and Facebook only learned they may not have from news reports this week. In the interview with CNN, he said Facebook erred in accepting the assurances of Cambridge Analytica and Mr Kogan.
“I’m used to, when people legally certify that they’re going to do something, they’re going to do it. But I think this was a mistake in retrospect”, Mr Zuckerberg said. “We should not have trusted the certification they gave us”, he added, “and we’re not going to make that mistake again”.
In his post, Mr Zucckerberg said Facebook had instituted safeguards in 2014 to prevent apps from harvesting the amount of user data gleaned by Mr Kogan’s survey and pledged Facebook would roll out more stringent measures to limit data collection. He reiterated the pledge to better safeguard user data during the CNN interview, promising a sweeping review of existing apps.
“We are doing a set of things to restrict the amount of access that developers get going forward“, he said, adding that “We’re going to review thousands of apps”.
While Mr Zuckerberg’s statement hewed to the explanation already publicly offered by Facebook, it came after Mr Zuckerberg faced rising frustration from elected officials who wondered why the CEO had not publicly addressed the gathering crisis.
Members of Congress and Parliament have called on Mr Zuckerberg to testify, and his post did not quell their desire to hear from the Facebook founder himself.
“The steps Facebook has laid out to protect its users are a start but Zuckerberg still needs to come testify”, said Senator Amy Klobuchar, a Minnesota Democrat who has sought to more tightly regulate political speech on Facebook.
Similarly, Senator Ed Markey, a Massachusetts Democrat, responded to Mr Zuckerberg’s post by writing “You need to come to Congress and testify to this under oath”.
“I still want to know why it took Facebook so long to do anything about this, particularly when there are indications that this user data was exploited by Cambridge Analytica for years”, said Senator Mark Warner, a Virginia Democrat.
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