"In response to Canada's continued inaction and retaliation, President Trump has found it necessary to increase the tariff on Canada from 25 per cent to 35 per cent to effectively address the existing emergency," the White House said.

The White House also said that Trump has further modified reciprocal tariff rates.

"The president has determined that it is necessary and appropriate to modify the reciprocal tariff rates for certain countries," it said in a fact sheet.

This is a developing story. Refresh for updates.