The European Union wants to engage swiftly with the United States over President Donald Trump's planned tariffs, trade chief Maros Sefcovic said on Tuesday, while his boss Ursula von der Leyen forecast negotiations with Washington would be tough.

The tool, which was drawn up during Trump’s first term and subsequently used as a deterrent against China, allows the EU’s executive arm to impose restrictions on trade in services if it determines that a country is using tariffs on goods to force changes in policy.