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.

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.

The amount of goods would be about four times larger than the last time Trump targeted the bloc’s metals sector.

The trade threats could reduce exports to the United States and dampen investment in Europe, dealing a blow to growth at a time when the continent is already facing a lackluster economy.

The European Union estimated that the first wave of tariffs on steel and aluminium imposed by US President Donald Trump will result in a hit to EU exports worth up to €28 billion (approx. US$29.3 billion).