It has already laid out a measured response.

From mid-April, a first package of EU tariffs worth up to €26bn will be slapped on US goods, in retaliation for 25% US tariffs on EU steel and aluminium exports which were already announced in March. These had been put back to give space for a negotiated solution. If they go ahead they’ll cover a wide range of agricultural, food and textile goods.

Discussions are currently under way on an even bigger package of countermeasures that are due to come in at the end of April.

In von der Leyen’s words, Europe “holds a lot of cards”. Further measures would not just include US goods, but potentially its digital services too.

Trump complains about the US trade deficit with the EU, but with services the US has a €109bn trade surplus with the EU, according to Brussels.

If the EU decides to impose tariffs or restrictions on Big Tech services or limiting US access to public contracts, it could use what some have labelled its “big bazooka” – more drily known as the Anti-Coercion Instrument (ACI)., external

That would need majority support from EU member states, but it is a powerful weapon when Europe’s businesses are under threat.

Peter Dige Thagesen, head of geopolitics at the Danish Industry board, told the BBC that Trump “threw a hand grenade right into global trade, creating enormous uncertainty”.

He said US tariffs would hit smallest companies that exported to the US the hardest. While the EU had to respond proportionately, he said it had to keep negotiating to avoid a deeper trade war.

While the majority of European leaders were quick to condemn the US tariffs, Hungarian Foreign Minister Peter Szijjarto laid the blame squarely at the EU’s feet. Hungary’s leader, Viktor Orban, is widely seen as Trump’s biggest ally in Europe.

“It has again been proven that in Brussels incompetent people are leading the European institutions, who are also suffering from a very serious Trump-phobia,” said Szijjarto.

Although Norway is not an EU member state, Prime Minister Jonas Gahr Store said the US decision to impose a 15% tariff was “bad news” that would have consequences for many Norwegian companies and jobs.

Norway is primarily an exporter and Finance Minister Jens Stoltenberg fears it could be hit by a “triple squeeze”. Not just by Trump tariffs and lower growth, but by the EU’s countermeasures too.

It could be a trade war with many casualties.

Additional reporting by Giulia Tommasi in Rome.