European leaders said they would respond firmly to higher levies on steel and aluminum, but they had yet to say what that retaliation would look like.

The European Union vowed a response to 25% tariffs President Donald Trump said the US will impose on steel and aluminum imports, escalating a potential trade dispute between transatlantic allies.

French steelmaker Aperam on Tuesday called on Brussels to intervene to curb imports if new 25% tariffs on all steel and aluminium imports into the United States prompt companies to ship more to the European Union instead.