This week President Trump signed an order imposing 50 percent tariffs on a wide array of Canadian exports in retaliation for Canada’s retaliation on his earlier tariffs, and some Canadian premiers were soon urging even more revenge. Doug Ford, Ontario’s premier, called on Ottawa to block or limit exports of potash, important minerals and energy, including oil and electricity. All of those items, which are among Canada’s largest exports, are excluded from the new tariffs taking effect on Aug. 19. “They need to feel the pain,” Mr. Ford said. The tariffs dominated talk at the premiers’ annual summer meeting this week in ... (full story)