Back in NAFTA (negotiations, anyway): A second round of negotiations got off to a tense start Friday in Mexico City after U.S. President Donald Trump threatened to pull the trigger for his country to exit the deal. Mexico responded with a message that if he did, it would not be opposed to walking as well. Canada is playing the nice-guy-stuck-in-the-middle role with Trudeau reiterating his optimism that the others won't pack up their toys and leave.