President Trump and the European Union might have struck a trade deal, but tensions between them over technology regulation persist. Mr. Trump offered European leaders a painful reminder of that early on Tuesday morning.

As Europe slept, the American president threatened tariffs and restrictions on countries seen as unfairly regulating U.S. tech firms.

“Digital Taxes, Digital Services Legislation, and Digital Markets Regulations are all designed to harm, or discriminate against, American Technology,” he posted on Truth Social, opening a new and potentially contentious chapter in the world’s continuing trade fight.

The post does not call out the European Union specifically, but Mr. Trump and other key administration officials have made it clear for months that they are unhappy with how the 27-nation bloc treats big American technology companies including X and Meta.

Republicans including Vice President JD Vance have criticized an E.U. law, called the Digital Services Act, that requires social media companies to more aggressively police their platforms for illegal content and disinformation. Mr. Vance and other officials argue the law places as an unfair burden on American platforms and undercuts free speech.

This month, Marco Rubio, the U.S. secretary of state, instructed American diplomats to lobby against the rules. And on Monday, Reuters reported the administration was contemplating sanctions against E.U. officials who were responsible for enacting the key digital regulation.