U.S. President Donald Trump has threatened to slam Canada with more tariffs over its wildfires polluting America. 

In a post on Truth Social on Friday, the U.S. President blamed Canadian authorities for failing to maintain their forests, causing wildfires that pollute the U.S.

“We are holding Canada responsible for the fact that they are not properly maintaining their Forests, and Brush therein, and the United States is being unnecessarily invaded by filthy, polluted, and unhealthy air, the quality of which is dangerous, and totally unacceptable!,” Mr Trump said.

He also promised to call the Canada Prime Minister, Mark Carney, to find out what the country was doing about the situation. 

Describing wildfire ravaging Canada as wilful negligence, Mr Trump said “The cost is incalculable! Canada has refused to engage in basic Forest Management and Debris Removal, knowing that such refusal will lead to exactly this result. 

He added, “This is willful negligence, and becoming a yearly occurrence, costing the United States Billions of Dollars, which cost of this pollution must of necessity be added to the TARIFFS Canada is currently paying.”

With almost a tenth of the world’s total forest area, Canada has experienced massive wildfire in its forest often causing smoke pollution across neighbouring North American countries, including the U.S. in recent years.

The smoke has spread across several U.S. states, including Minnesota, Michigan, Pennsylvania, Ohio and New York, prompting “hazardous” air quality alerts in many areas and forcing the cancellation of numerous outdoor events.

In an open letter addressed to Canadian officials, U.S. lawmakers John James, John Moolenaar, Jack Bergman and Lisa McClain said their “patience has run out.”

“We are done accepting apologies in place of action,” they said, warning that the US could explore direct involvement in cross-border wildfire protection and firefighting if Canada failed to act.

“We were told last year that this would be treated with urgency. It was not,” they claimed, adding that instead “American lungs are paying the price for Canadian inaction, year after year.”

This year alone, Canada has recorded over 3,500 total wildfires clearing up to 2.38 million hectares (5.9 million acres) landmass.

The Canada prime minister, Mr Carney, in a statement on Thursday, said, “The wildfire situation has escalated significantly over the last three weeks across the country, and particularly in North-Western Ontario.”

According to Mr Carney, thousands of people have been forced to evacuate their communities, not knowing if their homes will survive.

Commending firefighters, first responders, Indigenous and local leaders working tirelessly to keep people safe, Mr Carney said his “government is in close contact with provincial, municipal, and Indigenous partners and stands ready to provide any additional support as needed.”