Épernay | French champagne producers do nearly $US1 billion ($1.6 billion) worth of business with the United States every year. But now in Épernay, the world capital of sparkling wine, the only number on anybody’s lips is 200.

That is the per cent tariff US President Donald Trump has threatened to impose on champagne and other European wines and spirits exported to the United States, in a trade war that exploded this past week after the European Union countered Trump’s penalties on steel and aluminum with its own duties on US products.