Several Facebook employees have been using the company's well publicized signature wall to protest the Black Lives Matter movement, and CEO Mark Zuckerberg is not happy about it.

In a private letter sent to employees Thursday, Zuckerberg addressed incidents in which some of his staff members crossed out "Black Lives Matter" and replaced it with "All Lives Matter" on the wall, Gizmodo reports.

In the memo obtained by Gizmodo, Zuckerberg condemned the actions saying that he was "very disappointed by this disrespectful behavior." He also addressed some of the controversy facing the movement.

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"There are specific issues affecting the Black community in the United States, coming from a history of oppression and racism. 'Black Lives Matter ' doesn't mean others lives don't — it's simply asking that the black community also achieve the justice they deserve."

Although the phrase "Black Lives Matter" become a rallying cry in 2012 following the death of unarmed black teenager Travyon Martin, it has been criticized for being too ethnocentric and misguided.

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In August 2015 Sen. Rand Paul (R-KY) told Fox News that the movement should change their name to "something that does not emphasize concern about racial justice" and expressed support for "All Lives Matter," according to Think Progress.

In November, a video surfaced of a protestor being beaten and dragged out of a Donald Trump event in Alabama; the man was wearing a Black Lives Matter T-shirt. As he was being hauled out of the area, a Trump supporter yelled "All Lives Matter," according to the Guardian.

However, as Ian Millhiser argues in ThinkProgress, the phrase "All Lives Matter" ignores the "special burden carried by people of color."

Recently, Black Lives Matter co-founder Marissa Johnson condemned the phrase "All Lives Matter" in an interview with Fox News.

"All lives matter is a new racial slur. White Americans have created the conditions that require a phrase like ‘Black Lives Matter."

Facebook is currently investigating the incidents.