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.

Mexico, Canada and the European Union on Tuesday condemned U.S. President Donald Trump's decision to impose tariffs on all steel and aluminum imports next month, a move that has fanned fears of a trade war as business and political leaders braced for yet more trade duty announcements from the new administration.

President Donald Trump signed an order Monday imposing global tariffs of 25% on all steel and aluminum imports in a move that will likely please domestic steelmakers but hurt allies like Canada and Mexico.