So far, the European Union has managed to stay out of the escalating trade tensions between the U.S. and China. Along with other U.S. allies, it negotiated for itself a temporary exemption from the tariffs on imported steel that President Donald Trump announced last month, citing national security concerns.

Since then, the U.S. has introduced a further $50 billion of tariffs on an extensive list of Chinese imports in retaliation for what it claims is theft of intellectual property and has threatened a further $100 billion....