Facebook CEO Mark Zuckerberg reprimanded employees for replacing “Black Lives Matter” slogans with “All Lives Matter” on the walls of the company’s headquarters in San Francisco.

In a private Facebook post obtained by Gizmodo, Zuckerburg told employees that their behaviour was “malicious” and “disrespectful,” and reminded them that there are “specific issues affecting the black community in the United States.”

“This has been a deeply hurtful and tiresome experience for the black community and really the entire Facebook community, and we are now investigating the current incidents,” said Zuckerberg.

Zuckerberg went on to encourage employees to take part in the “Black@ town hall” on the 4th of March to “educate themselves about what the Black Lives Matter movement is all about.”

The Facebook CEO is not the only Silicon Valley bigwig to express his support for Black Lives Matter, a movement that has wreaked havoc on US campuses and cities. Twitter CEO Jack Dorsey is a well-known Black Lives Matter supporter who marched alongside protesters in Ferguson, Missouri and is acquainted with movement leader DeRay Mckesson.

Zuckerberg’s comments come as the company takes an increasingly tough approach to monitor and remove “hate speech” across the platforrm, working with Angela Merkel and the German government, who are particularly concerned with “hate speech” against migrants. It also comes as other silicon valley companies like Twitter and GitHub become increasingly reckless about displaying their political biases.

“All Lives Matter” is a slogan that developed in response to “Black Lives Matter.” It has been defended by Tim Scott, South Carolina’s first black senator since the reconstruction, as a more unifying slogan than the latter.

“If it causes offense that I say that ‘all lives matter’ — black lives, white lives, police officers, jurists, all of us, even politicians, all of our lives matter — if that is somehow offensive to someone, that’s their issue, not mine,” Scott told CNN last September.

“If we’re saying that the country has a provocative history on race, I affirm that fact,” he stated. “But for under the circumstances, to find a way forward, it is truly together.”

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