The Trump administration sees tariff talks as a chance to pressure a rival into concessions. E.U. officials have acted as though they were dealing with an ally.

Calling the European Union "very difficult to deal with," President Donald Trump said Friday the United States would move to enact a 50% tariff on the EU.

Trump’s advisers have privately expressed irritation to European officials that EU member nations’ differing trade priorities have slowed down the talks, according to people familiar with the discussions.