President Trump said Sunday that Americans may feel "some pain" as a result of the North American trade war that's emerging after he imposed sweeping tariffs on Mexico and Canada. Retaliatory tariffs were quickly announced by Mexico, Canada and China, which the president also targeted with import duties. John Yang speaks to Kirsten Hillman, Canadian ambassador to the U.S., for more. PBS News is supported by - https://www.pbs.org/newshour/about/funders