Will the US-Canada tariff war irrevocably damage bilateral ties?

FOR most of the post-war era, the world’s longest undefended border also marked its most integrated economic relationship. That era is now, by most honest accounts, over – or at least on indefinite pause. 

Last Saturday (Aug 22), after three days of talks in Washington collapsed, the US imposed 50 per cent tariffs on roughly US$20 billion of Canadian goods. 

Canadian Prime Minister Mark Carney answered with a promise to match the penalties “dollar for dollar”, and on Tuesday announced retaliatory tariffs on about US$20 billion of US imports, effective Sep 8. 

It is the latest, and among the sharpest, escalations in a trade fight that has run for a year and a half with no durable resolution in sight.

The start of the trade war

The conflict can be traced back to February 2025, when US President Donald Trump imposed sweeping tariffs on Canadian imports: 25 per cent on most goods and 10 per cent on energy, citing border security and trade imbalances. 

Canada, then under the administration of Justin Trudeau, countered within days, and the value of goods subject to Ottawa’s tariffs swelled from roughly C$30 billion (US$21.7 billion) to C$155 billion within weeks. 

What followed was more than a year of tit-for-tat measures touching steel, aluminium, autos, dairy, lumber and consumer products. 

They were punctuated by temporary exemptions, a change in Canadian leadership, and a US Supreme Court ruling in February 2026 that struck down several of the emergency tariffs Trump had imposed under his claimed authority granted by the International Emergency Economic Powers Act – a decision that briefly narrowed, but didn’t end, the dispute.

Talks aimed at a broader settlement, tied to the renewal of the US-Mexico-Canada trade agreement, dragged through months.

They finally broke down for good late last week. Each side blames the other. US Trade Representative Jamieson Greer said Canada reneged on terms “agreed earlier this week” and made new demands that upended a “careful balance”. 

Carney countered that Washington’s late proposals were “uneconomic” and that the US “asked too much, and offered too little”, undermining any reliable path to a deal.

Justifications on both sides

There is a case for the American position. Washington argued it is responding to a year of Canadian retaliation and unresolved irritants, from dairy market access to border enforcement. 

Tariffs, according to the Trump administration, are a legitimate tool to force concessions from a trading partner that has, in US eyes, resisted structural reform. 

Supporters of the administration’s approach noted that the current tariffs cover only about 5 per cent of Canadian exports to the US, a calibrated pressure point rather than an economy-wide rupture, and that renegotiating continental trade terms after three decades is not unreasonable.

There is an equally credible Canadian case. Canada has been the target of an alliance-shaking rhetorical campaign by the Trump administration, including talk of the country becoming the US’ “51st state”, alongside tariffs that Carney described as designed to “hurt and divide” the country.  

From Ottawa’s vantage point, Canada offered real concessions: dropping retaliatory tariffs on steel, aluminium and autos, and restoring US alcohol on Canadian shelves – only to see Washington add new demands at the eleventh hour. 

For instance, the Trump administration wanted a say in Canada’s trade negotiations with other countries, according to Carney.

Carney’s framing – that economic integration itself was “used as a weapon” – resonates with a broader Canadian anxiety that decades of continental interdependence became a point of leverage for the US rather than mutual benefit.

What’s actually at stake

It’s worth being honest about scale. The tariffs that triggered this weekend’s rupture are, in dollar terms, modest – a slice of a trading relationship worth roughly US$760 billion annually. Neither side’s officials described them as economy-altering on their own. 

The larger cost is structural: the erosion of predictability that made North American supply chains in autos, agriculture and energy profitable in the first place. 

Businesses on both sides of the border have already begun rerouting sourcing and investment decisions around the assumption that this bilateral tie is no longer stable.

The political dimension compounds this. Polling suggests a large majority of Canadians now want their country to rely less on the US, a sentiment that predates but has hardened through this dispute. This is visible in boycotts of American goods and a fall-off in cross-border travel.

That kind of shift in public sentiment tends to outlast any single administration or negotiating round. Even a comprehensive framework, if one is eventually reached, may not fully repair a relationship that both governments now openly describe in adversarial terms.

A fight for economic sovereignty

Neither government appears to be bluffing. Both Canada and the US show no sign of backing off their tariffs. The renewal of the broader continental trade agreement – the real prize, and the real source of long-term certainty for businesses – is now entangled with this breakdown rather than separate from it.

What seems clearest is that both sides have legitimate grievances and that neither has a monopoly on strategic error. 

Washington’s approach carries the risk of trading short-term leverage for long-term alienation of its closest ally. Ottawa’s posture risks prolonging a costly stand-off while it searches for diversification that will take years, not months, to materialise. 

The tariffs making headlines this week are a symptom of a deeper structural argument – about how much economic sovereignty either country is willing to trade for the efficiencies of integration – that talks alone are unlikely to resolve quickly.