Trump and Trudeau
President Donald Trump and Canadian Prime Minister Justin Trudeau

Michael Kappeler/DPA via ZUMA

Canada officially implemented tariffs on about $12.5 billion worth of US goods Sunday, the latest offensive in the growing trade battle between the United States and other major economic powers. US exports of steel and other metal products now face a 25-percent tax, while other products—such as milk, ketchup, beef, and yogurt—will be taxed at 10 percent.

The tariffs come in direct response to the Trump administration’s own tariffs on Canadian steel and aluminum, which have also affected Mexico, China,…