Trade experts hail ‘new era of protectionism’ with targeted countries retaliating with their own tariffs

• US politics – live updates

Donald Trump’s threat to impose steep tariffs on goods imported into the US has set the stage for a bitter global trade war, according to trade experts and economists, with consumers and companies warned to brace for steep costs.

The president-elect announced on Monday night that he intended to hit Canada, Mexico and China with tariffs on all their exports to the US – until they reduce migration and the flow of drugs into the country.