Pushed by Trump, Canada enters a new era of economic nationalism

As trade negotiations with the United States sputtered over the summer, Prime Minister Mark Carney started talking about a new, domestically oriented solution for Canada's tariff-battered industries. "We have the potential to become our own best customer for steel, but we will lose that ability if we don't manage the profound transformation now under way in the industry," Mr. Carney said from the floor of a metal fabrication plant in Hamilton in mid-July as he unveiled a bundle of measures to keep out foreign steel and boost domestic demand for Canadian mills. A few weeks later, he announced a support…