Washington DC, July 18 -- US President Donald Trump on Friday (local time) warned of increasing tariffs on Canada, accusing Ottawa of failing to properly manage its forests and prevent wildfire smoke from affecting air quality in American cities.

In a post on Truth Social, Trump said the United States was being impacted by what he described as "filthy, polluted, and unhealthy air" from Canadian wildfires and said the cost of the pollution would be added to tariffs currently imposed on Canada.

"We are holding Canada responsible for the fact that they are not properly maintaining their forests, and brush therein, and the United States is being unnecessarily invaded by filthy, polluted, and unhealthy air, the quality of which is dangerous,...