A different take on the cause of the collapse from the American side:
“Despite the US offer to Canada to receive the best treatment of any major exporter to our market,
new demands and walk-backs of other commitments by Canada have upended the careful balance reached in the past days,” US Trade Representative Jamieson Greer told reporters on a press call shortly before midnight, the Associated Press reported.
…
The tariffs that are now going into effect are relatively limited in scope, covering about $20 billion worth of goods imported from Canada — roughly 5% of the total value of goods imported to the US from its northern neighbor last year.
On their own, they are unlikely to meaningfully impact American consumers, who are already getting squeezed by higher gas prices. The greater issue is the trade war it is starting.”
So who to believe. Certainly not Team Carney. As inferentially pointed out by CNN, Canada isn’t relevant anymore to the US economy. Yes there’s a trade war, but they’ll replace Canada within months.