After a discussion at an EU summit in Brussels, leaders said in a statement the bloc would "reserve its rights, in compliance with World Trade Organization rules, to respond to the US measures as appropriate and in a proportionate manner."

Mr. Trump on Thursday authorized the suspension of controversial tariffs on steel and aluminum imports from key trade partners including the European Union, but only until May 1.

Trump's exemption landed just before a Friday deadline, and came after eleventh hour talks in Washington between EU Trade Commissioner Cecilia Malmstroem and top US officials.