Europe’s worst-case scenario for the future of transatlantic economic relations rose to the surface this week when President-elect Donald Trump gave a clear signal that he’ll use American trade might as a means to exert foreign policy leverage.

A pledge by President-elect Donald Trumpto impose tariffs on products from Canada, Mexico and China sent their currencies lower against the dollar on Tuesday, renewing the specter of trade wars and fanning uncertainty in other currency pairs.

At a conference in Paris, corporate chiefs, finance ministers and top politicians called for a “Europe First” policy to counter Donald Trump’s protectionist agenda.