Former Ku Klux Klan leader David Duke has been permanently banned from Twitter after breaking the platform’s rules regarding hate speech.

It's unclear what exactly Duke tweeted that prompted the prohibition, but the company said the decision was due to “repeated violations of the Twitter rules on hateful conduct,” according to ABC News.

The platform's hateful speech policy prohibits promoting violence, inciting harm or threatening attacks against people based on religious affiliation, race, ethnic origin and other protected categories.

“You may not promote violence against or directly attack or threaten other people on the basis of race, ethnicity, national origin, caste, sexual orientation, gender, gender identity, religious affiliation, age, disability, or serious disease,” the policy states.

Twitter stated these guidelines were put in place so everyone is able to share “without barriers” and because experiencing abuse on the platform will make people hesitant about posting.

“Our role is to serve the public conversation, which requires representation of a diverse range of perspectives,” the company explained. “We are committed to combating abuse motivated by hatred, prejudice or intolerance, particularly abuse that seeks to silence the voices of those who have been historically marginalized.”

Twitter defines violent threats as “declarative statements of intent to inflict injuries that would result in serious and lasting bodily harm, where an individual could die or be significantly injured.”

The site has a zero-tolerance policy for violent threats and said accounts violating that policy will face immediate and permanent suspension.

“Slurs, epithets, racist and sexist tropes, or other content that degrades someone” is prohibited as well.

Twitter recently updated its guidelines on links, which now includes hateful conduct and violence.

Duke had been an active Twitter user since 2009 with over 53,000 followers, according to Business Insider.

His YouTube channel was suspended in June, along with that of Richard Spencer and others who promoted hate and white supremacy. YouTube said the channels violated its hate speech guidelines.

"We have strict policies prohibiting hate speech on YouTube, and terminate any channel that repeatedly or egregiously violates those policies," the platform said in a statement according to Business Insider.

Twitter has been more strictly enforcing its rules, including against President Donald Trump, who has been censored multiple times for violating policies regarding abusive behavior. In late June, Trump's tweet suggesting people who tried to create the now-dissolved Autonomous Zone in Seattle would be "met with serious force” was flagged by the social media site because it included a “threat of harm against an identifiable group,” reports CNBC.

Because he is a world leader, Trump's harmful tweets are flagged with a public interest notice that informs people it violates policy while still allowing people to view it instead of being removed, per Twitter's guidelines.

Trump’s son, Donald Trump Jr., also had his account suspended temporarily after spreading misinformation regarding the coronavirus, reports CNN. Trump Jr. posted a video from a doctor who said face masks were not needed to prevent the spread of the virus.