The European Union on Friday threatened tech billionaire Elon Musk with sanctions after Twitter removed several journalists that report on him and the social media company.

Vera Jourova, the European Commission’s vice president for values and transparency, said in a tweet that news of the “arbitrary suspension of journalists on Twitter is worrying.”

Late Thursday, Twitter abruptly suspended several high-profile journalists who cover him, including CNN correspondent Donie O’Sullivan and Ryan Mac, a reporter at The New York Times.

He suggested these journalists violated Twitter’s policy on “doxxing,” or exposing a person’s identifiable information.

It comes after the account @ElonJet, which tracked the location of Musk’s private jet using publicly available flight data, was suspended by Twitter.

Musk now faces possible sanctions from the EU.

“EU’s Digital Services Act requires respect of media freedom and fundamental rights,” said Jourova. “This is reinforced under our #MediaFreedomAct. @elonmusk should be aware of that.”

“There are red lines. And sanctions, soon,” she added.

Jourova didn’t add any further details on the sanctions. Under the EU’s Digital Services Act, companies can be fined up to 6% of their global annual revenues for breaches.

The DSA, which entered into force on Nov. 16, requires large platforms to reduce harms online, implement protections for users’ rights and issue transparency reports.

Big Tech platforms are required to report the number of active end users they have to the Commission by February 2023. They then have until four months after the bloc completes reviews of the numbers to comply with the rules.

Musk has served as Twitter’s CEO since October after buying the company for $44 billion.

The Tesla and SpaceX boss, a self-described “free speech absolutist,” has troubled politicians and civil liberties activists with steps to restore the accounts of banned users, including former U.S. President Donald Trump, and the laying off of thousands of Twitter’s employees.