Retaliatory tariffs issued by Canada are set to hit some imports from the United States soon after midnight on Tuesday, intensifying a trade war between the longtime allies and risking an escalation from President Donald Trump.

Levies as high as 50% will be applied to hundreds of U.S. products, ranging from aluminum foil to raincoats to cheese. U.S. elected officials in states bordering Canada, including Republican Sen. Susan Collins of Maine, have warned the trade dispute will hurt local businesses and consumers.

Canadian officials said the retaliatory measure would target about $20 billion worth of U.S. products, mirroring the size of a recent batch of U.S. levies. The targeted goods amount to nearly 6% of annual U.S. exports to Canada, according to U.S. Census Bureau data for 2025.

A tit-for-tat trade war erupted last month after official negotiations collapsed and a fresh round of U.S. levies took hold. Within days, Canadian officials announced what they described as matching tariffs that would begin in the second week of September.

The Canadian tariffs, which target many products included in a batch of U.S. levies last month, are set to take effect at 12:01 a.m. Eastern Time on Tuesday.

Trump has repeatedly warned of a forceful response if the Canadian tariffs were to take hold. He vowed, for instance, to ratchet up tariffs from 25% to 50% on Canada-made cars and auto parts beginning in January.

“On Trade, and in other ways, also, they are among the worst Nations in the World to deal with,” Trump said on his social media platform late last month. “They feel entitled, and yet, WE DON’T NEED CANADA, THEY NEED US!”

Trump signed an executive order on Aug. 27 changing the name of Lake Ontario to “Lake America.” Days later, Trump posted on social media an AI-generated video of birds with Trump’s signature hairstyle marching with firearms to protect a body of water labeled “Lake America.”

Canada said it will continue referring to the lake as “Lake Ontario.” In a post on X late last month, Canadian Prime Minister Mark Carney said, “This lake is called Lake Ontario — today and forever.”

Carney rebuked the Trump administration further last week, saying U.S. public messaging signaled an unwillingness to negotiate a resolution.

“When the Americans stop doing memes, stop throwing shade and stop trying to be tough, and start being serious about having those discussions, we can have those discussions,” Carney said.

In the first half of 2026, the U.S. exported $175.8 billion in goods to Canada — the second biggest export trading partner after Mexico — accounting for 14% of all U.S. exports, according to the Census Bureau.

For now, levies apply to a sliver of goods that travel between the U.S. and Canada, limiting the impact of the trade dispute, but a potential escalation threatens to deepen the pain for both economies.

“This is a classic trade-war situation: Somebody puts on a tariff, another country retaliates dollar for dollar and then more tariffs are added,” Campbell Harvey, a professor at Duke’s Fuqua School of Business who studies commodity markets, previously told ABC News. “Then we get into this really bad equilibrium.”