X, the platform formerly known as Twitter, may have broken the European Union’s tough new Digital Services Act rules, regulators said as they announced the opening of a formal investigation today. A key concern of the investigation is “the dissemination of illegal content in the context of Hamas’ terrorist attacks against Israel,” the European Commission says.

In a press release, the commission said it will look at X’s attempts to counter the spread of illegal content on its platform and will examine X’s efforts to stop “information manipulation” via its Community Notes system and other policies. It’s also looking into matters beyond content moderation, including “deceptive design” relating to “the so-called Blue checks,” advertising transparency, and data access for researchers.

This is the first time the commission has launched formal proceedings under the DSA, the regulator said. The EU announced the so-called “Very Large Online Platforms,” or VLOPs, to be regulated under the DSA in April 2023. Alongside X, the list included 16 other platforms and two search engines including Meta’s Facebook and Instagram, TikTok, Snapchat, LinkedIn, Amazon, Google Search, and Apple’s App Store.

“The higher the risk large platforms pose to our society, the more specific the requirements of the Digital Services Act are,” said Margrethe Vestager, EU executive vice president. “We take any breach of our rules very seriously. And the evidence we currently have is enough to formally open a proceeding against X.”

“Today’s opening of formal proceedings against X makes it clear that, with the DSA, the time of big online platforms behaving like they are ‘too big to care’ has come to an end,” said Thierry Breton, EU commissioner for internal markets.

The announcement of the formal investigation comes a little over two months after Breton raised initial concerns over the spread of “illegal content and disinformation” on X. The company responded to Breton by outlining its moderation efforts, noting that it had removed “hundreds” of Hamas-affiliated accounts and removed or labeled “tens of thousands of pieces of content.” The commission followed up with a formal request for information. Similar requests were also sent to Meta and TikTok.

Following the start of the Israel-Hamas war, there have been widespread reports of disinformation / misinformation spreading on X about the conflict, including videos and images being shared out of context, a propaganda network of dozens of accounts sharing false and inflammatory content, and X’s failure to take down posts that violate its own rules. A report from NBC News suggested that X’s Community Notes feature has struggled to keep up.

Since his purchase of X (then known as Twitter), new owner Elon Musk has cut back its trust and safety team, overhauled its verification system to allow anyone to pay for a “blue check,” and reinstated numerous previously banned accounts.

Shortly after the European Commission’s announcement, X posted a statement via its official Safety account, calling for the process to follow the law and be “free of political influence.” “X remains committed to complying with the Digital Services Act and is cooperating with the regulatory process,” the statement said. “X is focused on creating a safe and inclusive environment for all users on our platform, while protecting freedom of expression, and we will continue to work tirelessly towards this goal.”

The commission says that its next steps will be to gather evidence and that it may take interim enforcement action against X. There is no legal deadline for when formal proceedings like this must be brought to an end.

Update December 18th, 8:22AM ET: Updated to add X’s statement.