Donald trump has never been shy about expressing his fondness for tariffs. But prior to his return to the White House, many of his supporters thought it more of a negotiating ploy: an aggressive stance meant to prod other countries into concessions. This comforting story now looks like fantasy. Mr Trump has shown himself to be a true believer in trade protectionism. In the process he has raised the average effective tariff on goods entering America from 2.5% last year to about 20%, the highest since the Great Depression.