TORONTO (AP) — For decades, Canada built much of its prosperity on privileged access to the United States. Now, after the collapse of trade talks, one of the world’s closest and most durable alliances has been fundamentally altered, with both countries facing the risk of a full-scale trade war.Prime Minister Mark Carney acknowledged the break after last-ditch negotiations failed Friday, saying Canada had recognized that “America has changed” and that the countries would “not return to our old relationship.”The United States imposed 50% tariffs on about $20 billion worth of Canadian goods early Saturday. Canada promised to match the import taxes dollar for dollar. Carney suspended negotiations and ordered Canada’s trade team home after accusing Washington of last-minute changes that were “unfair, uneconomic, and called into question the reliability of any deal.”

Carney foreshadowed the shift at the World Economic Forum in Davos in January, declaring that the world was experiencing “a rupture, not a transition” and urging countries such as Canada to reduce their vulnerability to economic coercion by strengthening their economies at home and diversifying abroad.“The collapse of the tariff talks points to the fact that the old Canada-U.S. relationship is over and, for many Canadians, it also confirms the perception that Canada can’t trust the Trump administration,” said Daniel Béland, a political science professor at McGill University in Montreal.