Trade negotiations between the United States and Canada have broken down, with escalating tensions over tariffs and trade relations. US President Donald Trump has rejected potential agreements and announced tariff measures, whilst Canadian Finance Minister Mark Carney has countered by preparing significant tariff retaliation in response to Washington's protectionist stance.

The conflict has taken an unusual symbolic turn, with Trump publicly stating that US business expectations with Ontario have diminished and joking about renaming Lake Ontario to "Lake America"—a waterway jointly managed under a 1909 treaty. Whilst the renaming lacks legal force, it exemplifies the increasingly unprecedented and confrontational rhetoric accompanying the bilateral trade breakdown.