Donald Trump’s tariffs are a headache for all his trade partners. But the U.S. president’s plan to impose ad hoc “reciprocal” levies on imports are a particular problem for the European Union. By enabling him to target whichever countries in the bloc he pleases,

Over $600 billion in European goods were imported by the U.S. last year. New tariffs from President Trump will likely hit these popular categories the hardest.

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.