Washington says it offered Canada its best terms. The 50% tariff now looks like the settlement.

Greer's phrasing works against a resumption. If the offer on the table was already the most preferential extended to any American trading partner ^[1], Washington has nothing left to add later without conceding that the first description was sales copy. Ottawa is in the mirror position: Carney called the terms "unfair" and "uneconomic" ^[4], which makes accepting anything similar later a domestic cost rather than a win. He then suspended negotiations ^[7]. Two public positions, neither with a face-saving exit, and an empty calendar ^[6]. That is the shape of a regime, not a posture.

The arithmetic explains why it can hold. More than $20bn of goods sits behind the 50% line ^[3], against the nearly $2 trillion in annual North American trade the USMCA framework covers ^[8]. That is roughly 1% of the flow ^[15]. The wall is narrow. The bill is not: about $10bn in added cost if Canadian exporters hold their current US volumes, on the source's own reckoning ^[10], which is close to a fifth of the $48.3bn 2025 US deficit with Canada that Washington treats as the grievance ^[9][14]. A measure that is small in coverage and large in cash is exactly the kind that survives, because the aggregate trade numbers will not scream while the pain concentrates in manufacturing and natural resources ^[11].

The agenda that failed makes the durability more awkward. The two sides were working on critical minerals, energy provisions and security access ^[5]. Canada supplies minerals essential to EV batteries, semiconductor production and defense applications ^[12], and remains one of the largest suppliers of oil and natural gas into the US market ^[13]. The tariff lands on the same categories the talks were meant to lock down. If Carney's dollar-for-dollar match arrives at the promised scale, American exporters going north absorb roughly another $10bn ^[16], so the combined annual cost of not signing is about $20bn against a deficit of $48.3bn.

Worth keeping the provenance in view. Everything about the rejected offer comes from the US side, via Greer, with no terms published beyond his characterization ^[17]. Buyers on either side of the border cannot audit "most preferential" and have no reason to expect the text. What both governments have put on the record is the rate and the absence of a meeting.