Elon Musk said Monday that X, formerly known as Twitter, has no choice but to file a defamation lawsuit against the Anti-Defamation League amid an ongoing slump in advertising revenue.

Musk said the tech giants advertising revenue was down 60% in the U.S. following his acquisition of the company last year for $44 billion. His tenure has been rocky, to say the least: X has laid off thousands of staffers and Musk has enacted dramatic changes to limit features, paywall others and promote the site as a new bastion for free speech. That included an amnesty program for suspended accounts that prompted groups including the ADL to warn the changes would lead to an increase in harassment and hate speech.

But Musk said he blamed the fall in ad dollars on the ADL which works to combat hate against Jewish people saying the group had falsely accused X and Musk of being antisemitic.

Based on what weve heard from advertisers, ADL seems to be responsible for most of our revenue loss, Musk wrote on Monday. Giving them maximum benefit of the doubt, I dont see any scenario where theyre responsible for less than 10% of the value destruction, so ~$4 billion.

The ADL said it does not comment on legal threats but added the attacks were on par with those seeking to limit the civil rights watchdog.

ADL is unsurprised yet undeterred that antisemites, white supremacists, conspiracy theorists and other trolls have launched a coordinated attack on our organization, a spokesperson for the group said. This type of thing is nothing new.

The ADL noted that it recently participated in the 60th Anniversary of the March on Washington and met with executives at X, acts that clearly upset these hateful groups.

Such insidious efforts dont daunt us, the spokesperson continued. Instead, they drive us to be unflinching in our commitment to fight hate in all its forms and ensure the safety of Jewish communities and other marginalized groups.

X filed suit in August against the Center for Countering Digital Hate, saying it had spread false claims about a surge in hate speech on the platform.