U.S. President Donald Trump says the United States will hold Canada responsible for wildfire smoke blowing into American airspace and that he plans to add tariffs as retaliation. In comments posted Friday, Trump accused the Canadian government of “willful negligence,” arguing Canada is not properly maintaining its forests and brush and that the resulting smoke has worsened air quality across parts of the Midwest and East Coast. Several outlets report Trump characterized the air as “filthy, polluted, and unhealthy” and said he would contact Canadian Prime Minister Mark Carney as part of the dispute.

Other reporting highlights that the Trump approach is part of a wider Republican push to punish Canada for transboundary wildfire smoke. A U.S. senator and members of Congress have proposed sanctions or urged Canada to take immediate action. At the same time, more diplomatic messaging from some U.S.-Canada officials is also noted, including the U.S. ambassador to Canada describing the fires as a “shared challenge” requiring a “shared response,” with both countries monitoring and exchanging information in real time.

The White House has not been detailed about how any tariffs would be imposed or how their rates would be determined, according to one account.