OTTAWA(National Times)- President Donald Trump on Friday blamed Canada for wildfire smoke spreading across the United States and said he would add the “incalculable cost” of dealing with the pollution to existing tariffs on Canadian goods.

Heavy smoke from hundreds of Canadian fires enveloped a swathe of the US from the midwest to the northeast on Thursday and Friday, prompting warnings to residents to stay indoors.

Trump, who has a combative relationship with Prime Minister Mark Carney, said he would be calling the Canadian leader to find out what he planned to do about the “totally unacceptable” situation.

“We are holding Canada responsible for the fact that they are not properly maintaining their forests … and the United States is being unnecessarily invaded by filthy, polluted, and unhealthy air,” he said in a Truth Social post.

“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.”

Shortly after taking office, Trump imposed tariffs on several key imports from Canada.