In the early hours of Tuesday, Canada enacted $20 billion in retaliatory tariffs on American goods, a measured but forceful answer to the Trump administration's own sweeping levies on Canadian exports. The move marks not an impulsive reaction but the culmination of months of failed diplomacy, wounded sovereignty, and deepening mistrust between two nations whose fates have long been intertwined. What began as a border security dispute has grown into something larger — a reckoning over the terms of partnership itself, and whether agreements between neighbors can hold when one side questions the