There was a time when the United States and Canada could disagree over almost anything without questioning the foundation of their relationship itself.
They disagreed over lumber, dairy, over the Iraq war, clashed on climate policy, pipelines, trade rules and occasionally those negotiations turned bitter. But beneath all of it was an assumption so deeply ingrained that neither country needed to say it out loud: whatever the disagreement, Canada and the United States remained neighbours, allies and economic partners, and the relationship itself was never really in doubt.
But Donald Trump has broken that assumption. This dispute feels different from those that came before, and the relationship has now reached the point of no return.
