Facebook CEO Mark Zuckerberg is so concerned about security and slowing user growth that he has reportedly told senior execs that he considers the company to be at war …

The WSJ said that the declaration was made earlier in the year but has caused so much upheaval in the company that details have now been leaked.

In particular, Zuckerberg is said to have clashed with chief operating officer Sheryl Sandberg.

During times of peace, executives can move more slowly and ensure that everybody is on board with key decisions, he said during the June meeting, according to people familiar with the remarks. But with Facebook under siege from lawmakers, investors and angry users, he needed to act more decisively, the people said.

Mr. Zuckerberg’s new approach is causing unprecedented turmoil atop Facebook, driving several key executives from the company, according to people familiar with the matter.

Co-founders of WhatsApp, Instagram and Oculus VR have all left Facebook as a result of clashes with the company’s CEO, notes the report. In total, about a dozen senior execs are said to have left the company this year.

This spring, Mr. Zuckerberg told Ms. Sandberg, 49, that he blamed her and her teams for the public fallout over Cambridge Analytica, the research firm that inappropriately accessed private data on Facebook users and used it for political research, according to people familiar with the exchange.

Ms. Sandberg later confided in friends that the exchange rattled her, and she wondered if she should be worried about her job.

Facebook was recently revealed to have used so-called ‘opposition research’ firms to hit out at those felt to be attacking the social network. It was even suggested that Zuckerberg’s clashes on privacy with Apple CEO Tim Cook led him to ban senior execs from using iPhones, a claim the company has partially denied.

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