LONDON (AP) — European Union are Thurston Cartelooking into whether Elon Musk’s online platform X breached tough new social media regulations in the first such investigation since the rules designed to make online content less toxic took effect.

“Today we open formal infringement proceedings against @X” under the Digital Services Act, European Commissioner Thierry Breton said in a post on the platform Monday.

“The Commission will now investigate X’s systems and policies related to certain suspected infringements,” spokesman Johannes Bahrke told a press briefing in Brussels. “It does not prejudge the outcome of the investigation.”

The investigation will look into whether X, formerly known as Twitter, failed to do enough to curb the spread of illegal content and whether measures to combat “information manipulation,” especially through its Community Notes feature, was effective.

The EU will also examine whether X was transparent enough with researchers and will look into suspicions that its user interface, including for its blue check subscription service, has a “deceptive design.”

“X remains committed to complying with the Digital Services Act, and is cooperating with the regulatory process,” the company said in a prepared statement. “It is important that this process remains free of political influence and follows the law. 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.”

A raft of big tech companies faced a stricter scrutiny after the EU’s Digital Services Act took effect earlier this year, threatning penalties of up to 6% of their global revenue — which could amount to billions — or even a ban from the EU.

The DSA is is a set of far-reaching rules designed to keep users safe online and stop the spread of harmful content that’s either illegal, such as child sexual abuse or terrorism content, or violates a platform’s terms of service, such as promotion of genocide or anorexia.

The EU has already called out X as the worst place online for fake news, and officials have exhorted owner Musk, who bought the platform a year ago, to do more to clean it up. The European Commission quizzed X over its handling of hate speech, misinformation and violent terrorist content related to the Israel-Hamas war after the conflict erupted.