US President Donald Trump has warned that he may impose fresh tariffs on Canada after smoke from hundreds of uncontrolled wildfires spread across large parts of the northern United States, causing dangerous air pollution and disrupting daily life in several major cities.

The comments came as some American lawmakers blamed Canada for the worsening air quality, while Canadian officials called for cooperation instead of criticism.

Trump Blames Canada for Smoke Crossing Into the US

Trump criticised Canada over the wildfire crisis in a post on Truth Social, claiming the United States was suffering because of Canada's failure to manage its forests.

“The United States is being unnecessarily invaded by filthy, polluted, and unhealthy air,” Trump wrote. He added that his administration was considering new tariffs because of what he described as Canada’s “willful negligence”.

Trump also said he planned to speak with Canadian Prime Minister Mark Carney to demand an explanation. He accused Canada of “not properly maintaining” its forests and brush, arguing that poor forest management had worsened the wildfire situation.

Hundreds of Wildfires Continue to Burn Across Canada

Canada continues to face one of its most severe wildfire seasons. According to the Canadian Wildland Fire Information System, there were around 888 active wildfires across the country as of Friday. Most of these fires remained out of control.

Ontario has been among the hardest-hit provinces, with more than 190 active wildfires. Several of these fires are still burning without containment, making firefighting efforts extremely challenging.

Ontario Premier Calls for US Support

Ontario Premier Doug Ford rejected criticism from the United States and instead urged Washington to provide assistance in controlling the fires. Ford said both countries should work together to tackle the emergency rather than exchange accusations, as the scale of the wildfire crisis requires cross-border cooperation.

Canada has not officially responded to Trump's tariff warning. However, Prime Minister Mark Carney had earlier stressed that climate change and the growing threat of wildfires are shared challenges that require both Canada and the United States to work together.

Political Debate Intensifies

The wildfire emergency has also reignited political debates in the United States. Some Republican lawmakers and supporters revived Trump's long-standing proposal that Canada should become the 51st US state. The suggestion has repeatedly been rejected by Canadian leaders and has angered many Canadians.

The proposal has also contributed to public frustration in Canada, with some people choosing to boycott travel to the United States.

Meanwhile, some social media users have even suggested delaying the opening of the Gordie Howe International Bridge, a Canada-funded infrastructure project connecting Ontario and Michigan.

Wildfire Smoke Creates Hazardous Air Across the US

Smoke from the Canadian wildfires spread across several northern US states, causing hazardous air quality and reducing visibility in many cities. The smoke covered much of the Manhattan skyline, while Chicago authorities closed city beaches because of poor air conditions.

States closest to the Canadian border, including Minnesota, Wisconsin, Michigan and Illinois, experienced some of the worst air pollution. Air quality also deteriorated across the Northeast, including New York.

Chicago and Detroit Among World's Most Polluted Cities

Air quality monitoring company IQAir reported on Thursday evening that Chicago and Detroit had become the most polluted cities in the world because of the wildfire smoke. New York also ranked among the world's most polluted major cities.

Authorities in New York warned residents that the smoke contained fine particulate matter that posed health risks to everyone across the New York metropolitan area and Long Island.

Health officials advised people, especially children, older adults and those with respiratory conditions, to limit outdoor activities until air quality improves.

Wildfires Continue to Impact Both Countries

The ongoing wildfire season has become a growing challenge for both Canada and the United States. While firefighters continue battling hundreds of uncontrolled blazes across Canada, the smoke is affecting millions of people south of the border, increasing health concerns and adding fresh political tension between the two neighbouring countries.