Canada's retaliatory tariffs took effect just after midnight on roughly $20 billion worth of U.S. goods, opening a high-profile trade standoff between President Donald Trump and Canadian Prime Minister Mark Carney. It is the latest round in a dispute that has unfolded since Trump returned to the White House wielding sweeping tariff actions against major U.S. trading partners, upending the largely tariff-free trading relationship the two countries had maintained under the U.S.-Mexico-Canada Agreement.

The measures follow the collapse of trade talks at the eleventh hour last month. Canada's tariffs impose duties of 15%, 25% or 50% on hundreds of American products, including steel, aluminum, dairy items such as milk and cheese, golf clubs, appliances, clothing and farm equipment. The targeted goods account for about 6% of the $333.6 billion in exports the United States sent to Canada last year. The tariffed list deliberately mirrors sectors hit by earlier U.S. measures, a pattern Ottawa has used before when responding to American trade actions.

Hours before the 12:01 a.m. ET deadline, Trump escalated his attacks on Truth Social, threatening a complete ban on aircraft sales from Canadian manufacturer Bombardier, vowing fairness for Americans and continuing his argument that the world treats the U.S. as a "piggybank" — a stance he had already made clear when he fired back at Canada after Carney suspended trade talks, accusing the U.S. of a last-minute "power play."

"NO MORE SELLING BOMBARDIER IN THE UNITED STATES! Their products aren't good enough!" Trump wrote. "Over 50% of their revenue comes from the United States — They live off American Buyers, American Companies, American Airports, and American Service — All while Canada blocks our GREAT American Banks, and Companies, throughout the U.S.A.

"They even blocked Gulfstream Aerospace from doing business in Canada — Completely unjust and unfair! That Era is OVER! If they want our Market, they must build here, and stop treating America like a "piggybank." BUY AMERICAN. FLY ON AMERICAN AIRLINERS. ENJOY AMERICAN LIQUOR AND BEVERAGES. SAIL ON LAKE AMERICA. AMERICA FIRST!"

The move against Bombardier drew pushback in Canada, where Quebec's premier called the U.S. tariff on the company an attack on Canada.

Canada has gone beyond tariffs in other ways. Eight of its 10 provinces continue to restrict or ban sales of U.S. alcohol. According to the Distilled Spirits Council, U.S. spirits exports to Canada fell more than 70% year over year after those restrictions took effect — a concrete early measure of how provincial countermeasures, which sit outside federal control, are already reshaping cross-border commerce.

Late last week, Trump warned that Canada making him "the enemy" would prove dangerous.

"It is very good for Canadian Politicians like Prime Minister Carney to make President Donald J. Trump "the enemy," until their Economy collapses, then it will be very bad for Politics — Worse than anything that has ever happened to a Canadian Politician," Trump wrote on Truth Social. "Just watch!"

Vice President JD Vance, speaking in Brewer, Maine, just three days after trade talks broke down, warned Canada against punishing farmers in border states like Maine with tariffs on agricultural goods while accepting U.S. military security and treating China better than the U.S. on trade.

"They treat Chinese goods more fairly than they do the goods that come from the people of Maine: It's insanity," Vance said. "And what we've said to Canada is stop it.

"I think that we should have a deal, but I think that we need to send a message loud and clear to the prime minister of Canada: Stop taking advantage of the people of Maine. Stop taking advantage of America. It's over."

Carney, for his part, has not been shy about drawing China closer as he leans into Canadian opposition to Trump's America First agenda.

"I believe the progress that we have made in the partnership sets us up well for the new world order," Carney said earlier this year in Beijing.

Chinese leader Xi Jinping is slated to visit the White House in two weeks.

Trump's aggressive trade stance toward Canada — which has included renaming Lake Ontario "Lake America" and threatening 50% tariffs on Canadian vehicles next year — has largely unified the Canadian public behind Carney's government. Canada nevertheless faces structural economic disadvantages, sending more than 70% of its exports to its southern neighbor, an asymmetry that has long shaped Ottawa's leverage in disputes with Washington.

Commerce Secretary Howard Lutnick detailed the last-minute snag in an Aug. 21 interview with Bloomberg Radio.

"It's Friday at 4 o'clock, we're signing it at like 6 or 7; there's no new topic that you're coming up with now," Lutnick said, pointing to a request for "heavy trucks." "And I said to him, 'Are you trying to blow this up?'

"And the answer was, and I quote, 'I'm not allowed to say that.'

"They decided for political reasons, domestically, domestic Canada, they'd rather fight with Donald Trump even if it's bad for the economy of Canada, for their political ambition to get certain election."

Canada suggested the fallout stemmed from objections to French-speaking Quebec.

"We don't care about their language," Lutnick added. "This is the Canadian Liberal Party using their economy to get themselves elected even if they're selling their own citizens down the river. It's sad and disappointing, but that's just the way it is."

Trump has also urged Canadian companies to immediately move to the U.S., saying, "I don't want Canadian anything."

Carney — set to address the European Parliament next week after framing the conflict at Davos as a defense against foreign economic coercion — has maintained that negotiations can resume once Washington becomes serious. A day after Carney's Davos remarks, Trump responded by saying Canada "lives because of the United States" and warned: "Mark, remember that next time you make your statements."

A government source told Reuters there are currently no talks between the two sides at the level of ministers or government officials, leaving businesses and consumers on both sides of the border to absorb the new duties in the meantime.

"What we are worried about is an escalatory spiral," said Michael Harvey, executive director of the Canadian Agri-Food Trade Alliance and a member of Carney's advisory committee on bilateral U.S. economic relations. "But at the same time, we totally understand that the prime minister needs to find areas of leverage.

"The Canadian government needs to keep channels open to the United States and not go overboard in terms of rhetoric and reacting to the rhetoric from the American side, while waiting for the American decision-making process to come back to economics."

U.S. Trade Representative Jameison Greer said Canada turned its back on the "best deal."

"We offered them the best deal. They looked at it square in the face and turned around," he told Fox News' "Special Report" on Thursday. "It wasn't good enough to have the best deal in the world. They wanted it to be even better."

The Associated Press and Reuters contributed to this report.