OTTAWA - Senior business and political leaders from Canada, the United States and Mexico are joining forces to establish a blueprint for a powerhouse North American trading bloc to take on the world, shielded by a Fortress America-style defence perimeter. The trinational task force, which has the full backing of the three governments, has been charged with creating a road map toward a continent-wide customs-free zone with a common approach to trade, energy, immigration, law enforcement and security that would virtually eliminate existing national borders. John Manley, the former Liberal deputy prime minister, will co-chair the task force and be...