Canada's trade negotiations with the US collapsed on Saturday morning, prompting Prime Minister Mark Carney to declare "we got attacked" and vow a firm response, hours before 50% US tariffs on Canadian exports were due to take effect. The breakdown, and Canada's decision to walk away from a deal that appeared near completion, marks a significant escalation in North American relations and reflects a broader sense among Canadians that their long-standing alliance with the US has fundamentally ruptured, with implications for western unity beyond trade.

Canada plans dollar-for-dollar retaliatory tariffs from 8 September, while Carney said last-minute US demands were "uneconomic" and undermined trust in any agreement, a claim Washington disputes. Canadian ambassador Mark Wiseman said no single issue killed the deal, but disagreements over autos tariffs, digital and cultural policy, and US claims to a veto over Canada's other trade alliances proved decisive; Carney noted that US commitments are sometimes "written in pencil". Despite the economic cost, Canadian public opinion has swung behind Carney, driven less by technical trade disputes than by a feeling of betrayal over shared security ties, with commentators accusing the US of using tariffs to assert dominance over its northern neighbour.