Six members of Congress from Wisconsin and Minnesota have asked Canada to say how it plans to tackle the blazes and reduce the haze billowing south.

Canada is one of the United States' top trading partners, with more than $410 billion of goods crossing into the country last year.

Trump threatened to escalate tariffs beyond 35% if Canada opts to retaliate with tariffs on U.S. goods. Canadian goods are also subject to sector-specific tariffs, such as 50% levies on steel and aluminum as well as 25% tariffs on non-USMCA compliant autos and auto parts.

Tariff negotiations between the two top trading partners are on a different track from those the U.S. is pursuing with other nations. But Canada may not get a better outcome.

President Donald Trump published a letter to Prime Minister Mark Carney on Thursday, accusing Canada of having "financially retaliated" against the U.S.

If implemented, Trump's new 35 percent duties will be "separate from all Sectoral Tariffs," such as the 50 percent tariff on steel and aluminum imports. Trump also promised that, if Canada raises its own tariffs in response, then "whatever number [Canada chooses] to raise them by, will be added onto the 35% that [the U.S. charges]."

Canada is seeking to finalise a free trade deal with Southeast Asian nations as part of a push to expand into new markets, its top diplomat said, responding to the hefty tariffs imposed on it by the United States,

The country with the most favorable view of the United States was Israel, with 95% viewing it as an ally and 1% viewing it as a threat. Mexico, meanwhile, had the least favorable responses, 37% viewing the United States as an ally and 68% a threat.