Canadian Prime Minister Mark Carney said on Saturday that Canada was "at war" over trade with the United States and that, starting September 8, the country would impose tariffs on imports of US steel, electronics and other products in retaliation for US President Donald Trump's new 50% tariffs that took effect at midnight.

"Canada will match Washington's new tariffs dollar for dollar in order to protect Canadian workers, farmers, families, and businesses," Carney said at a news conference.

When asked whether Canada was engaged in a trade war, Carney said, "You're at war when you get attacked. We got attacked."

After days of intense negotiations, Canada and the US did not reach a trade deal late on Friday, worsening a delicate relationship between the long-term trade partners and allies, and complicating the future of the North American free trade pact involving the pair and Mexico.

Trump's new tariffs hit sectors including wine, furniture, dairy products, cement, clothing, fishing rods and hockey equipment, and cover some $20 billion of Canadian exports to the US. These duties do not exempt Canadian products under the continental trade agreement, which had shielded most Canadian exports to the US in the last 18 months.

While outlining Canada's position after trade talks with the US broke down, Carney said the Canadian counter-tariffs will cover a wide range of sectors, including dairy, steel, appliances, agricultural equipment, pulp and paper, and electronics, along with some sectors the US previously targeted in Canada. The government will release details over the next several days, he added.

Explaining why negotiations broke down at the last minute, Carney said that while both sides were close to a mutually beneficial agreement earlier this week, the US side introduced last-minute changes that were "unfair, uneconomic and called into question the reliability of any deal."

"We cannot accept what they have offered, and we will not give what they have asked," Carney said.

The US side's repeated disregard for existing free trade agreements such as the Canada-United States-Mexico Agreement (CUSMA) sends a bad signal to international businesses and is "certainly not good news" for renewing the agreement in the future, Carney warned.

US Trade Representative Jamieson Greer told Fox News on Saturday that no new talks are planned with Canada.

"We're moving forward with measures that respond to Canadian retaliation," Greer said. "They've always had the best deal, and they still would have an even better deal, but they didn't want that."

The rift comes as the United States, Mexico and Canada are trying to renew CUSMA, a trade agreement that Trump negotiated in his first term and once praised as a triumph.

The United States has begun formal talks with Mexico to revamp the agreement, but talks with Canada have not yet begun.

CUSMA is a trilateral trade pact that replaced the North American Free Trade Agreement when it took effect on July 1, 2020. On July 1, 2026, the United States officially declined to renew the agreement for another 16-year term, triggering an annual review process until the pact expires in 2036.

'Under no illusions'

Carney is one of the few global leaders to retaliate against US tariffs and has pledged to forge new trade and military alliances, despite Canada's dependence on the United States for nearly 70% of its exports.

Beyond the latest tariffs, relations between Canada and the US have suffered from Trump's repeated threats to make Canada the 51st US state.

The US president was also irked by Carney's widely touted January speech at the World Economic Forum in Davos, Switzerland, in which the Canadian prime minister declared that the global order was experiencing a "rupture."

The Canadian leader has repeatedly said that relations with the US have been forever changed and that the country must reduce its reliance on its southern neighbor.

"We've been under no illusions. We recognized from the start that America has changed," Carney told reporters on Saturday.

Wang Ruibin, director of the Department of World Economics and Development at China Institute of International Studies, said the latest tit-for-tat tariffs between the US and Canada will carry a political impact that outweighs the economic one, particularly as political trust between the two countries has already been eroded.

"A series of US actions have repeatedly exposed its unreliability as an ally, a close neighbor, and a key trading partner to Canada, dealing a blow to the very foundation of what is often described as the world's closest bilateral economic and security relationship," Wang told China Media Group.

"That is a damage that cannot be measured merely in terms of GDP losses."

(With input from agencies)