WASHINGTON — A mandatory review of the Canada-U.S.-Mexico-Agreement on trade kicks into high gear this year as US President Trump continues his campaign to realign global trade and poach key industries from America’s closest neighbours. …Since the president’s return to the White House, however, confidence in CUSMA’s future has waned. Trade with Canada may not be front of mind for Trump, said Fen Osler Hampson, a professor of international affairs at Carleton University in Ottawa and co-chair of the Expert Group on Canada-U.S. Relations. It’s more like the “proverbial iceberg,” he said. “It’s what you don’t see that matters. And that’s the kind of hidden economic wiring of a very deep and highly interdependent relationship.” …Trump has complained repeatedly about long-standing irritants in the United States’ trade relationship with Canada — the supply management system for dairy products, the alleged subsidization of the softwood lumber sector, other non-tariff barriers.