Commission President Ursula von der Leyen said unjustified tariffs would prompt "proportionate and decisive countermeasures", echoing her vow on Tuesday of a "firm and proportionate" response to Trump's decision to impose tariffs on all steel and aluminum imports.

The commission’s response comes after Trump instructed staff to create tariffs on countries he sees as having unfair trade policies with the U.S.

The European Union hopes to avert a damaging trade war with the U.S. over impending metals tariffs by prioritising negotiations rather than retaliatory countermeasures, EU officials signalled on Wednesday.