New tariffs kicked in Saturday on billions of dollars' worth of U.S. imports from Canada after trade talks between the two nations collapsed. Canada said it intends to impose retaliatory tariffs starting Sept. 8, sparking the risk of a wider trade war.

Here's what to know about the new levies.

Which items will be subject to the new U.S. tariffs?

The tariffs, announced in late July, impose a surcharge of 50% on a long list of Canadian goods. Items subject to the levies include wine, hockey sticks, cement, natural honey, essential oils and candles. They also include various paper, textile and electronic products. The White House said at the time that some sectors and goods, including energy, potash and fish, would be exempt. Unlike previous taxes, the new round of tariffs doesn't exempt exports that comply with the U.S.-Mexico-Canada trade agreement.

Still, the tariffs on about $20 billion of imports affect only a fraction-about 5%-of what the U.S. purchases from its northern neighbor. In 2025, the U.S. imported $383 billion of goods from Canada.

Products already subject to tariffs under earlier national-security measures, including steel, aluminum, auto parts and lumber, won't be hit by this latest round, the White House said.

Why did talks break down?

Talks between the two nations had appeared to be going well, leading President Trump to extend the initial deadline for the tariffs. But U.S. Trade Representative Jamieson Greer told reporters the talks had failed on Friday night, despite what he described as the administration's willingness to give Canada the "best treatment" of any major U.S. trading partner.

Canadian Prime Minister Mark Carney said the U.S. proposed new terms in recent days that made reaching an agreement untenable. He didn't provide details, but said the terms involved the treatment of some kinds of automobiles, restrictions on Canada's ability to enter other trade deals and infringements on Canadian culture and sovereignty.

The terms "were uneconomic, unfair and undermined the net benefits for Canada, and called into question the reliability of any deal," he said.

The White House didn't immediately respond to a request for comment on Carney's remarks.

What is Canada doing in response?

Canada will impose dollar-for-dollar retaliatory tariffs on the U.S., Carney said, and offer support for affected Canadian workers. He said U.S. goods subject to the levies will be concentrated in sectors such as steel, dairy, appliances, agricultural equipment, paper and electronics.

Full details will be announced in the coming days, he said, and the tariffs will go into effect on Sept. 8.

Responding to a reporter's question about whether Canada was entering a trade war, Carney said: "You're at war when you get attacked. We got attacked."

Why did Trump impose the tariffs?

The White House said it imposed the tariffs in response to what it described as Canada's discrimination against U.S. goods, citing policies that require companies to invest in auto production in Canada and bans imposed by some Canadian provinces on American liquor products.

The two nations have exchanged tariffs for months. Trump last year imposed emergency levies on Canada over its alleged role in the fentanyl trade, though the Supreme Court later deemed those tariffs illegal. He has also taxed Canadian steel, aluminum, auto parts and lumber on national-security grounds.

Many Canadian countertariffs have since been rolled back, although several provinces have maintained their retaliatory bans on U.S. wine and spirits.

Does Trump have the authority to impose the new levies?

Trump is relying on Section 338 of the Trade Act of 1930, an obscure portion of U.S. trade law. That law allows the president to tax countries that discriminate against U.S. companies-but it has never been used to justify tariffs and could attract legal challenges, experts say.

The law is written relatively broadly and appears to give wide discretion to the president, leading some trade lawyers to believe Trump could be more successful with these levies than with the sweeping global tariffs the Supreme Court struck down in February. Nevertheless, legal challenges to the new taxes could lead to months more uncertainty for businesses and consumers.

This explanatory article may be periodically updated.