“The European Union treats us very badly, and they have for years,” Donald Trump told the reporters in the Oval Office as Ireland’s taoiseach shifted uncomfortably in his seat next to him.

The US had slapped the EU with 25 per cent tariffs on steel and aluminium a few hours earlier. But the next front in the trade war will be fought over American tech giants such as X, Google, Facebook, Apple and Amazon.

Cheered on by “tech bros” including Elon Musk and Mark Zuckerberg who have rallied to support Trump, the US is heaping pressure on the EU to water down its disinformation rules for the social media titans or face more painful tariffs.

Brussels sources believe this is nothing less than an assault on the EU’s “regulatory sovereignty” and one that poses an “existential” threat to Ursula von der Leyen’s European Commission.

The first shots were fired in February. In a naked attempt to influence foreign legislation, Mr Trump issued a memorandum threatening tariffs against countries that imposed “overseas extortion and unfair fines and penalties” on US tech firms, which include some of the world’s most valuable companies.

Later that month in Munich, JD Vance, the US vice-president, evoked a culture war over tech. He likened EU officials regulating disinformation online to Soviet Union “commissars” crushing freedom of speech with red tape and warned the new White House expected its allies to share its “values”.

On Friday, Mr Musk, now working for the administration, posted a picture on X of the EU flag with a yellow hammer and sickle in its blue centre and the motto: “Imagine you love so much being governed that you want a government for your government.”