Ottawa, Canada - Deputy Prime Minister Chrystia Freeland, in a surprise announcement on Monday, quit over disagreements with Justin Trudeau on Canada's response to US President-elect Donald Trump's tariff threats.

"Our country today faces a grave challenge," Freeland, who also served as finance minister, said in a letter posted on X, pointing to Trump's planned 25% tariffs on Canadian imports.

"For the past number of weeks, you and I have found ourselves at odds about the best path forward for Canada," she added.

First elected to parliament in 2013, Freeland joined Trudeau's cabinet two years later when the Liberals swept to power, overseeing several key posts, including as trade and foreign minister, and leading free trade negotiations with the EU and US.

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But she said in her resignation letter Trudeau wanted to shuffle her to another job, to which she said: "I have concluded that the only honest and viable path is for me to resign from the cabinet."

As finance minister, Freeland explained the need to take Trump's tariff threats "extremely seriously."

"That means keeping our fiscal powder dry today, so we have the reserves we may need for a coming tariff war. That means eschewing costly political gimmicks, which we can ill afford and which make Canadians doubt that we recognize the gravity of the moment."

Canada's main trading partner is the US, with 75% of its exports going to its southern neighbor.