After appearing to take another prominent jab at the LGBTQ community’s use of gender pronouns on Sunday, billionaire entrepreneur Elon Musk got into a Twitter argument with former NASA astronaut Scott Kelly.

Musk, who took over Twitter in October, wrote, “My pronouns are Prosecute/Fauci,” referring to Dr. Anthony Fauci, the chief medical advisor to the White House.

Musk’s tweet gained a lot of attention and by Monday afternoon had 100,000 replies in addition to over 1 million likes.

Kelly, who has led three expeditions to the International Space Station, provided one of those responses. Sen. Mark Kelly, D-Ariztwin .’s brother and a retired astronaut, reprimanded Musk for his careless remark.

“Elon, please don’t mock and promote hate toward already marginalized and at-risk-of-violence members of the #LGBTQ+ community. They are real people with real feelings. Furthermore, Dr Fauci is a dedicated public servant whose sole motivation was saving lives,” Kelly wrote.

Musk, the CEO of Tesla and SpaceX in addition to running Twitter, pushed his point in response to Kelly.

“I vehemently object. It’s neither good nor kind to others to impose your pronouns on them without their consent, and to implicitly exclude those who don’t, Musk wrote.

Kelly claimed in an email to NBC News that he felt compelled to criticize Musk because the issue is “personal” to him and that he is aware of “the pain the hate causes” his gay and transgender family members.

He said, referring to his identical twin brother, “I feel obligated to correct people when they call me Mark. “I would feel obligated to correct people as well if they referred to me as she or her.”

Dr. Fauci has been vilified by the GOP, but Kelly said he believes the public health official did “what he thought was right to protect lives” while serving as the nation’s chief scientist during the majority of the Covid-19 pandemic.

As a supporter of science, he continued, “I feel compelled to defend science.”

Musk, who has a transgender daughter, has previously made comments on LGBTQ issues and faced backlash, particularly in relation to the use of pronouns that do not correspond with a person’s sex assigned at birth. This includes Sunday’s Twitter spat.

The billionaire tweeted “Pronouns suck” in July 2020 to express his opinions on pronoun usage. He went on to write: “I absolutely support trans, but all these pronouns are an esthetic nightmare” later that year to further explain his position.

A few days after publicly taking over the social media giant, Musk shared a link to an unfounded anti-LGBTQ conspiracy theory about the attack on House Speaker Nancy Pelosi’s husband, Paul Pelosi, in a since-deleted tweet. Without any supporting evidence, the conspiracy theory claimed that Pelosi’s attacker was actually a “male nudist hippie prostitute.”

Musk’s divisive tweets from Sunday are just the latest in a never-ending string of headlines the billionaire has created since he took control of Twitter.

He abruptly fired a significant portion of his staff just days after officially taking over the business, shocking everyone in the tech sector.

And in late November, Musk allowed former president Donald Trump to return to the platform, nearly two years after the company had banned him due to his involvement in the Jan. 6 Capitol insurrection. Other accounts that had been suspended in the past have also been restored by the multibillionaire CEO, including those of the anti-trans commentator Meghan Murphy and the fiery conservative Rep. Marjorie Taylor Greene, R-Ga.

Additionally, the business recently declared that it “no longer enforces the Covid-19 misleading information policy.”

Despite Musk’s repeated claims that the company has not changed any of its hate speech moderation policies, some of Twitter’s advertisers have reduced their spending on promotional placements on the site due to the uncertainty over what the platform will look like under his leadership.

Following his altercation with Kelly on Sunday night, Musk unexpectedly showed up on stage during comedian Dave Chappelle’s show in San Francisco, where he was greeted with boos and cheers. After a comedy special that many people thought was transphobic was released the previous year, Chappelle received harsh criticism from LGBTQ activists.