The European Union on Wednesday announced retaliatory trade action with new duties on U.S. industrial and farm products, responding within hours to the Trump administration's increase in tariffs on all steel and aluminum imports to 25%.

The world's biggest trading bloc was expecting the U.S. tariffs and prepared in advance, but the measures still place great strain on already tense transatlantic relations. Only last month, Washington warned Europe that it would have to take care of its own security in the future.