Canada and the United States appeared to be closing in on an agreement. Then everything fell apart. At midnight, threatened 50% U.S. tariffs took effect on roughly $20 billion of Canadian goods, Canada suspended negotiations and Mark Carney announced dollar for dollar retaliation. But now comes the critical question: What happened in those final hours? Carney says the United States introduced last minute changes that Canada considered unfair and economically unacceptable. The American side tells