US Trade Representative Jamieson Greer speaks outside the West Wing of the White House in Washington, DC, on August 26, 2026. The United States and Canada have plunged into a trade war as Ottawa stands its ground in the face of President Donald Trump's latest tariffs, taking on the world's largest economy. Washington slams its longtime ally as the only trading partner besides China to retaliate against Trump's duties. But Canadian Prime Minister Mark Carney said: "You're at war when you get attacked. We got attacked." (Photo by Jim WATSON / AFP via Getty Images)