Donald Trump’s threats of tariffs will do harm, even if he does not impose them

IT DID NOT take long. Even before getting into office, Donald Trump fired the opening shots in a new trade war. On November 25th America’s president-elect posted on social media that he would add an extra tariff of 10% on Chinese goods. But the shock was news of tariffs of 25% on Canada and Mexico as soon as he returned to the White House. These, he thundered, would remain in place until the two countries clamped down on drugs and migrants illegally crossing the border.