The Globe and Mail reports in its Wednesday, Aug. 12, edition that Canada's chief trade negotiator, Janice Charette, has warned United States officials that imposing new tariffs on Aug. 19 would represent a significant setback in negotiations. The Globe's Marieke Walsh and Adrian Morrow write that during a recent meeting with U.S. Trade Representative Jamieson Greer, she emphasized the potential backlash in Canada if President Donald Trump follows through on his tariff threats. Officials were warned that Ottawa couldn't control public or premier reactions, jeopardizing federal negotiations with Americans. Ms. Charette also told Mr. Greer that if the tariffs are imposed, Canada will be forced by the public to retaliate. Mr. Greer acknowledged Ms. Charette's message and recognized the political pressures the new tariffs would cause in Canada. A Canadian retaliation would almost certainly provoke a counterretaliation by Mr. Trump, ratcheting up the bruising trade war even further, such that Ms. Charette impressed on Mr. Greer that now was the window to reach a deal. Sources say U.S. officials are optimistic that a deal can be reached by Aug. 19, but they are worried about the ability to sell the pact in Canada.