X, the platform formerly known as Twitter, may have broken the European Union’s tough new Digital Service 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.

“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.