The announcement comes a day after the US auto giant said it projected a $4-5 billion hit this year from Trump's tariffs, despite moves earlier in the week by the president to dampen the blow.

GM's plant in Oshawa, Ontario "will return to a two-shift operation" from three, "in light of forecasted demand and the evolving trade environment," the company said in a statement.

"These changes will help support a sustainable manufacturing footprint as GM reorients the Oshawa plant to build more trucks in Canada for Canadian customers," it added.

It is expected to result in 700 out of 3,000 jobs cut at the plant, according to the auto workers' union.

"Today's news from GM is extremely tough for the workers in Oshawa and their families," Ontario premier Doug Ford said on X.

"In the face of economic uncertainty caused by the chaos of President Trump's tariffs and tariff threats, we will continue to fight every single day to attract new investment, secure good-paying jobs and support workers and their families," he added.

Trump in March announced 25 percent tariffs on imported automobiles, including from free trade partners Mexico and Canada, dealing a major blow to manufacturers who have developed highly integrated North American production lines.

His administration later granted partial exemptions for Mexico and Canada based on the value of American-made components.

US imports of auto parts are also set to face 25 percent tariffs beginning Saturday, with exemptions for parts compliant with the US-Mexico-Canada free trade agreement.

On Tuesday, Trump issued an order to minimize overlapping tariffs for automakers -- as he has also placed 25 percent levies on steel and aluminum imports -- and created a two-year "offset" process to reduce the immediate financial blow.