Ontario Premier Doug Ford said US criticism of Canadian efforts to stop the "terrible scenario" of spreading forest fires in his province and choking smoke across a broad swath of the United States was "absolutely unacceptable."

The Ontario premier noted that Canada has always been quick to send help and resources south of the border to deal with natural disasters.

Donald Trump has threatened to impose tariffs on Canada over wildfire smoke that is choking US cities.

Trump blamed Canada for wildfire smoke and called for more tariffs, accusing the country of mismanaging its forests.