The United States imposed 50 percent tariffs on $20 billion worth of Canadian products in Washington early Saturday after last-ditch negotiations failed. Canada said it would retaliate dollar for dollar, raising concern over the future of the North American trade pact. The breakdown followed an earlier deadline extension and left no further talks planned.

A worker secures a rolled coil of steel on a flatbed truck in at the ArcelorMittal Dofasco steel plant in Hamilton, Ont., Aug. 20. AP-Yonhap

WASHINGTON — The United States imposed 50 percent tariffs on $20 billion worth of Canadian products early Saturday, and Canada immediately said it would retaliate, after last-ditch negotiations failed to resolve the latest strain in already tense relations between the historic allies.

President Donald Trump’s import taxes will hit about 5 percent of what Canada ships to the United States every year, including products ranging from hockey sticks to tongue depressors.

Canadian Prime Minister Mark Carney said it would match the U.S. tariffs dollar for dollar, escalating the trade conflict and calling into the question the future of a North American trade pact between the United States, Canada and Mexico that is crucial to industry in all three countries.