Trump calls Canada "one of the worst countries to deal with" and vows to "take them on"

US President Donald Trump escalated his rhetoric against Canada, calling it "one of the worst countries to deal with" and promising to "take them on." The broadside is the latest in a string of insults directed at one of America's largest trading partners amid a deepening trade war. Canada has responded by imposing retaliatory tariffs on roughly $20 billion worth of US goods.