The president did not specify how much the tariffs would be or which nations could be targeted.
President Trump has made it clear that he is pushing for an end to the war in Ukraine. The move has left Europe worried that it, and Ukraine, could be left out as he negotiates with Russia’s leader, Vladimir V. Putin.
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 president imposed a 25 percent tariff on global metals, repeating a move from his first term. Economists and foreign governments know what will come next.