Wildfires in Ontario have expanded to more than 735,000 hectares, with 190 active fires forcing about 1,800 people to evacuate communities in the province’s northwest.

Smoke from the fires has improved in southern Ontario but continues to cause unhealthy air quality across parts of the U.S. Midwest.

The fires have also sparked political tensions after U.S. President Donald Trump criticized Canada’s wildfire response and threatened tariffs over the smoke.

Ontario Premier Doug Ford rejected the criticism, arguing Canada has consistently helped the U.S. during natural disasters and deserves support instead of blame, Reuters has reported.

Experts say increasingly severe wildfire seasons are being driven by hotter, drier conditions linked to climate change.