President Trump threatened on Friday to charge Canada tariffs to pay for harms caused by the wildfire smoke affecting American cities, joining a handful of Republican lawmakers who have criticized the Canadian government for what they claimed was poor forest management.
In a social media post, Mr. Trump said the United States was being “unnecessarily invaded by filthy, polluted, and unhealthy air, the quality of which is dangerous, and totally unacceptable,” and said he would call Prime Minister Mark Carney of Canada on Saturday to discuss the issue.
The president’s post followed earlier criticism toward Canada over the smoke from nearly 200 wildfires burning in Ontario, which is affecting millions of Canadians and has led to the evacuation of hundreds of people from communities across large swaths of the province. The smoke has swept across a number of U.S. cities, including New York, Detroit and Washington, causing hazardous air quality conditions over the past several days.
On Thursday, Mr. Carney did not directly address the accusations lobbed at his government by Republican lawmakers, but suggested the United States should do more to combat climate change, which scientists say is a significant factor in bigger, longer and fiercer wildfires. His office did not immediately respond to a request for comment on Mr. Trump’s Friday post.

Earlier on Friday, Doug Ford, the premier of Ontario, was visibly frustrated with complaints from American lawmakers about the smoke.
“As for other elected officials in the U.S., I have to remind the American people, when there was wildfires in California, we had our water bombers on standby,” Mr. Ford, a conservative, told reporters, listing other American disasters that Ontario has helped with. “If there’s some politicians out there chirping away, well, maybe what you should do rather than complain is send support, send help, because we have done the exact same thing for our American friends. And that’s what you’re supposed to do.”
As smoke from nearly 200 wildfires turned skies orange in many parts of the United States, four U.S. congressional members from Michigan on Wednesday wrote to Mr. Carney to accuse Canada of not properly managing its forests to prevent fires.
“Our hospitals are once again treating children, dialysis patients and older residents for the effects of smoke that did not originate anywhere near them,” the four Republicans — John James, Jack Bergman, John R. Moolenaar and Lisa C. McClain — wrote. “American lungs are paying the price for Canadian inaction, year after year.”
The representatives charged that Canada had not fulfilled earlier promises to improve its forest management and said that U.S. government agencies may begin “exploring direct involvement in cross-border fuel reduction and firefighting capacity.”
They added: “Sovereignty comes with responsibility, and the responsibility to prevent a foreseeable disaster from crossing into another country’s airspace has not been met.”
Under Canada’s division of powers, most forest lands are owned and managed by provinces, which collect royalties for commercial tree cutting and, with some exceptions like national parks, are also responsible for firefighting.
When asked generally on Thursday about complaints about Canadian fire smoke from American lawmakers, Mr. Carney pointed to the United States’ backtracking on climate change measures, including a shift away from renewable energy.
“The fight against climate change is the responsibility of all countries, including the United States,” he said, speaking in French.
Mr. Carney, a former United Nations special envoy on climate action and finance, has himself come under criticism from many environmentalists for reducing Canada’s carbon emissions targets and, most recently, agreeing to work with Alberta on building an oil pipeline to the Pacific Coast of British Columbia.
In May, Steven Guilbeault, a former environment minister and onetime member of Mr. Carney’s cabinet, resigned as a Liberal member of parliament because of that pipeline and what he called “backsliding” by the government on emissions reductions.
On Thursday, Mr. Carney, who calls himself an environmentalist, defended the reduced emissions targets as a recognition of Canada’s current reality. The pipeline, he noted, will only be built if Alberta’s oil sands producers also develop a multibillion-dollar system to capture and store their carbon emissions.
Mr. Ford said that his experiences with American governors during the ongoing fires have been a stark contrast to the tone of the letter from the Michigan lawmakers.
Mr. Ford particularly singled out Gov. Tim Walz of Minnesota who called looking for help in rescuing a Y.M.C.A. camp group from the state who were caught up in the fires.
“He is so, so grateful,” Mr. Ford said. “And I know the people of Minnesota are battling wildfires as well.”
Mr. Ford has also been criticized by his political opponents for budgeting 150 million Canadian dollars ($107 million) for the current wildfire season after spending 271 million dollars ($193 million) last year.
At his news conference, Mr. Ford said that the budget is just a base level and that the province will ultimately spend significantly more fighting the fires.
“In a time of a crisis, all levels of government need to come together, no matter if you’re opposition or not.” he said. “To go out there and try to scare people and put out blatant lies about the amount that’s spent is absolutely disgusting.”

