Trump said the new duties were justified by disputes over automobiles, alcohol, cheese and other products. The measures apply to roughly $20 billion in Canadian exports and reach goods that had previously moved under the Canada–United States–Mexico Agreement. Energy, potash, fish and several critical minerals were exempted, but the decision still threatens tightly integrated supply chains and higher prices on both sides of the border.

Carney called the action a direct challenge to the trade relationship and said Canada would intensify negotiations while keeping every response option available. The confrontation is about more than tariffs: it tests whether a smaller ally can resist economic coercion from its largest trading partner without surrendering the benefits of continental integration. Canadian leaders are signalling that negotiation remains preferable, but submission is not.