PARIS — Former European commissioner Thierry Breton urged the European Union to respond with “the utmost severity” to the Trump administration’s decision to sanction him and four other European nationals for their work on online content moderation.

U.S. Secretary of State Marco Rubio last week announced Breton would be “generally barred from entering the United States,” along with British citizens Imran Ahmed and Clare Melford and Germany’s Anna-Lena von Hodenberg and Josephine Ballon, all of whom were members of organizations seeking to fight hate speech online.

The U.S. State Department targeted Breton as the “mastermind of the Digital Services Act,” the EU’s rulebook for online platforms which was used to impose a €120 million fine on Elon Musk’s X and has led to a high-level dispute between Brussels and Washington.

“If we accept that, as a European Commissioner, you can be ostracized, blamed, and punished for carrying out the mandate entrusted to you, then we are heading down an extraordinarily dangerous path,” Breton said Tuesday on RTL. “If we allow this situation to continue, it would mean that those who succeed me and have to exercise their European mandate would be intimidated and prevented from doing so.”

“The European Commission cannot show any sign of weakness… European institutions must respond with the utmost severity,” he added.

Breton said he had spoken at length with French President Emmanuel Macron after being sanctioned. The former tech industry executive, who resigned from his role as commissioner for internal market last year over claims Commission chief Ursula von der Leyen was trying to push him out, has received widespread support in Europe since the U.S. decision against him.

In a statement, the Commission said it had “requested clarifications from the U.S. authorities” and would “if needed … respond swiftly and decisively.”