The Globe and Mail reports in its Wednesday 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. As previously reported, the two sides are aiming for an interim agreement in which Canada would agree to a long list of U.S. demands in exchange for some relief on Mr. Trump's tariffs. On Tuesday, one provincial government source said American alcohol would only return to the shelves if there is significant and meaningful progress on the 232 tariffs on steel, aluminum, autos and lumber. The source said there is no way premiers will fold on the alcohol ban simply in exchange for more talks.