The European Union told Elon Musk on Tuesday that he had 24 hours to explain plans to better counter Hamas videos on X, the site formerly known as Twitter.

In a letter posted on X, E.U. Commissioner Thierry Breton said that X, which Musk bought last year, “is being used to disseminate illegal content and disinformation in the EU.” He warned of an investigation and potential penalties if Musk or the platform didn’t respond.

“We have, from qualified sources, reports about potentially illegal content circulating on your service despite flags from relevant authorities,” Breton said.

A spokesperson for the European Commission, the legislative and enforcement arm of the E.U., said in an email that its concern was the proliferation of Hamas videos on the site, which violates both the Digital Services Act and its regulation against Terrorist Content Online.

“Content circulating online that can be associated to Hamas qualifies as terrorist content, is illegal, and needs to be removed under both DSA and TCO — as the organisations are listed on the EU’s terrorism list,” the spokesperson said.

In a statement posted on Monday, X’s @safety account said the company had “taken action under our Violent and Hateful Entities Policy to remove newly created Hamas-affiliated accounts and we’re currently coordinating with industry peers through @GIFCT_official to try and prevent terrorist content from being distributed online.”

X’s press team responded to an email requesting a comment with an automated reply that said, “Busy now, please check back later.”

Hamas caught Israel off guard in an attack over the weekend, which resulted in hundreds of civilians dead. False and misleading information about the attacks has spread widely across social media, but particularly on X, where users who pay to be verified get algorithmic boosts and seem to face little to no consequence for lying, sharing fake footage, or reusing old or virtual footage that they claim is new footage of the conflict. Under Musk’s ownership, the company has also repeatedly made cuts to its trust and safety teams.

One coordinated propaganda campaign on X falsely captioned videos of Russian officials saying that U.S. support for Israel would lead them to give military support to Palestine to escalate. It has received millions of views and many of its accounts are still visible.

“Public media and civil society organisations widely report instances of fake and manipulated images and facts circulating on your platform in the EU, such as repurposed old images of unrelated armed conflicts or military footage that actually originated from video games. This appears to be manifestly false or misleading information,” Breton said in the open letter.