Canada’s ambassador warns Trump tariffs are driving up costs, threatening U.S. investment

"Uncertainty increases your cost of capital," Ambassador Mark Wiseman said at the B20 summit , a gathering of global business leaders in Washington hosted by the U.S. Chamber of Commerce.

"If you're going to build a new plant, add a new shift, spend money on R&D, the more certainty you have, the more likely you're going to do that," said Wiseman, a former BlackRock executive who became Canada's ambassador in February.

His warning comes as Washington and Ottawa struggle to resolve a tariff quarrel affecting one of the U.S.'s largest trading relationships. The two countries exchanged roughly $570 billion in goods during the first nine months of 2026, according to U.S. Census Bureau data . That's an increase from the same period in 2025, the first year of Trump's second term, but lower than the comparable nine months during the previous three years, when Joe Biden was president.

Trump has defended his tariffs as necessary to protect U.S. manufacturers and workers, accusing Canada of discriminatory trade practices that disadvantage U.S. exporters.

The two governments have resumed negotiations after talks collapsed in August, with discussions focused on reducing tariffs on Canadian steel and automobiles. Trump has imposed duties of up to 50% on certain Canadian products , prompting retaliatory measures targeting billions of dollars in U.S. exports.

Wiseman called for the removal of tariffs imposed under Sections 232 and 338 of U.S. trade law, saying a resolution would help businesses make long-term investment decisions.

"The sooner, the better," he said.

Still, Canadian Prime Minister Mark Carney said Tuesday that the Trump administration remains Canada's principal negotiating partner.

"We've had comprehensive free trade with the United States since 1988," Wiseman said, describing Canada's objective as returning "as close as we can to free trade" while creating the certainty businesses need.

European ambassadors echoed those concerns at the B20 summit. Germany's ambassador to the U.S., Jens Hanefeld, said businesses could adapt to tariffs but struggled with an "ever-changing regulatory environment" that forced companies to spend more on lawyers to navigate shifting trade rules.

Speaking on the same panel, France's ambassador, Aurélien Lechevallier, urged greater cooperation on AI and energy rather than continued trade disputes.

"We've spent, I think, a lot of time the last years working and dealing with regulations, tariffs," he said. "Businesses are eager to do more business."

— Correction: This story has been corrected to reflect that Wiseman spoke about adding shifts to plants. A previous version misquoted the ambassador.