Mark Carney has been sworn in as Canada's new prime minister as the nation faces Trump's trade war. 'We're his largest client in so many industries,' Carney says.

Mark Carney was sworn in as Canada’s prime minister on Friday — and depending on the outcome of the next election, he could be the country’s shortest-serving leader.

To win the next election, the new prime minister must quickly prove he is Canada’s best hope of managing relations with the White House.