• SpaceX fired nine employees who shared an open letter in June, criticizing Elon Musk, per the NYT.

• Employees called on SpaceX to denounce Musk's "harmful Twitter behavior," per the report.

• Musk has recently fired Twitter employees for openly criticizing him on the platform.

SpaceX fired a total of nine employees who organized an open letter in the summer condemning the online behavior of CEO Elon Musk, The New York Times reported.

Some SpaceX employees circulated the letter on June 15, urging the company to denounce the billionaire's "harmful Twitter behavior," per The Times. The letter followed an Insider report in May about SpaceX settling a sexual harassment claim against Musk, which he made jokes about on Twitter.

The day after the letter was shared, SpaceX fired the organizers behind it, according to media reports. The Times reported it was unclear how many workers had been sacked, while Reuters said at least five employees had lost their jobs over the letter, citing two sources.

It's now understood that nine SpaceX employees were fired over the letter, The Times reported on Thursday, citing workers and lawyers.

The newspaper reported that charges alleging unfair labor practices were filed on Wednesday with the National Labor Relations Board involving eight of nine of the fired employees. The charges alleged it was against the law for SpaceX to fire the workers, per the report.

"Elon's behavior in the public sphere is a frequent source of distraction and embarrassment for us, particularly in recent weeks," employees wrote in the letter, obtained by The Times in June. They called on SpaceX to "separate itself from Elon's personal brand" and make clear that Musk's messaging "does not reflect our work, our mission, or our values."

Two SpaceX employees told the newspaper that the company held a meeting for 20 engineers the day after the firings. They said SpaceX's vice-president, Jon Edwards, said in the meeting that the employees behind the letter had been sacked for criticizing Musk and distracting the company, per The Times.