The European Union estimates that the first wave of Donald Trump’s steel and aluminum tariffs will hit as much as €28 billion ($29.3 billion) of the bloc’s exports in what would be a massive escalation in the US president’s trade war.

A top European Union official, who is trying to head off a potential trade conflict, stressed the importance of active engagement and fairness in trade during a four-hour meeting with Trump administration officials on Wednesday.

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,