President Trump and his trade team have threatened to tear up the North American Free Trade Agreement, and they want major concessions from Canada. Those talks turned ugly this week, with new U.S. tariffs already in place and Canada promising to retaliate July 1. The North Country's border towns are caught between the two sides. Much of the region's economy is integrated with that of Canada, and some business leaders worry that the trade battle is damaging a decades-old economic partnership.