Sarah Wynn-Williams, the former director of global public policy at Meta, appeared before the US Congress on Wednesday, accusing her former employer of reckless behaviour related to the company's desire to operate in China, possibly compromising American user data.
"Throughout my seven years at Meta I saw executives repeatedly undermine US national security and betray American values," she said during her opening testimony to the Senate judiciary committee. "They did these things in secret to win favour with Beijing and build an $18 billion business in China."
Ms Wynn-Williams accused Meta executives of engaging in illegal and dangerous activities to try to gain a foothold in China, which has been reticent about giving the social media platform a presence in the country.
She said that Meta allowed Chinese government officials to have a say in deleting expatriates' Facebook accounts over criticism of China, and offered officials certain tools that could be used to censor critics.
"I watched as executives decided to provide the Chinese Communist Party with access to Meta user data, including that of Americans," Ms Wynn-Williams said.
She said that because of Meta's closeness to Chinese government officials, the company's artificial intelligence model, Llama, was helping to improve China-based AI offerings such as DeepSeek.
During the hearing, Ms Wynn-Williams, who recently wrote a book about her time at the social media company, earned praise from the senators on the committee.
"This is a hearing that Facebook has tried desperately to prevent. Why is Facebook so desperate to prevent Sarah Wynn-Williams from disclosing what she knows?" asked Republican Josh Hawley during opening statements.
"Mark Zuckerberg worked hand in glove with China for years. He developed censorship tools for the Chinese company to be used against its own people."
Democrat Richard Blumenthal agreed.
"Mark Zuckerberg undermined US national security ... he tried to sell out America, he risked our national security and the individual security of everyday Americans, and they ought to be outraged," he said.
Ms Wynn-Williams's book, Careless people: A Cautionary Tale of Power, Greed and Lost Idealism, has been the subject of ample scrutiny.
The publisher, Macmillan, describes the book as a "searing memoir" that "exposes both the personal and the political fallout when unfettered power and a rotten company culture take hold".
The book makes reference to reported quirks and idiosyncrasies of those in positions of power at Meta, with claims that colleagues let founder Mark Zuckerberg win at board games, and accusations of an apparent lack of humanity for employees who suffered medical problems at work.
Ms Wynn-Williams was relieved of her duties at Meta in 2017.
Meta has gone to great lengths to try to hit back against the accusations made in the book, even trying to use the courts to prevent it from being sold.
“This is all pushed by an employee terminated eight years ago for poor performance," the company's spokesman, Andy Stone, posted to Meta's Threads platform. "We do not operate our services in China today.
"It is no secret we were once interested in doing so as part of Facebook’s effort to connect the world. This was widely reported beginning a decade ago. We ultimately opted not to go through with the ideas we'd explored, which Mark Zuckerberg announced in 2019."
The company also issued a point-by-point document titled Careless reprint: Sarah Wynn-Williams' new book of old news, in which Meta tried to debunk allegations in the book.
Yet Meta's efforts to debunk the book and blunt its impact seem to have had the opposite effect, as it reached the top of most best-seller lists in the US.
The congressional hearing comes at an inconvenient time for Meta, as it prepares for a lengthy court battle against the Federal Trade Commission, which has accused it of illegally stifling competition.
If Meta loses in court, it may be forced to spin off Instagram, WhatsApp and other social media and communication platforms it owns.
