'Willful negligence': Trump threatens Canada with tariffs as wildfires worsen air quality in US states

President Trump threatened Canada with tariffs over wildfire management after US lawmakers criticized Canada's fire response.

Ontario Premier Doug Ford called on Washington to send assistance to fight the fires instead of complaining.

Wildfires in Canada are worsening air quality in multiple US states.

The threat adds a trade dimension to a cross-border environmental and health issue.