The leaders of Canada and Mexico have criticised the latest hike in steel and aluminium tariffs under United States President Donald Trump, who increased import taxes on the metal from 25 to 50 percent.

The international condemnation came just hours after the latest tariff increase went into effect early on Wednesday.

Speaking to reporters on Wednesday, Canadian Prime Minister Mark Carney said the tariff increases were “unjustified”.

“They’re illegal. They’re bad for American workers, bad for American industry and, of course, for Canadian industry,” he said.

Mexican President Claudia Sheinbaum, meanwhile, pledged to pursue countermeasures if the Trump administration refuses to grant tariff relief. She warned that the tariffs would have a “huge impact” on Mexico’s steel and aluminium industries.

“This isn’t about an eye for an eye, but rather about protecting our industry and our jobs,” she added, without specifying what steps her government might take.

Canada calls for action

Wednesday’s tariff hike had been unveiled last Friday, when Trump held a rally with steelworkers outside Pittsburgh, Pennsylvania.

That region of the US is a part of the Rust Belt, an area that has been heavily affected by the decline in US manufacturing. Trump pledged to use tariffs and other measures to bring jobs and investments back to the area.

Previously, in March, Trump set tariffs on steel and aluminium at 25 percent. But he threatened to lift that rate to 50 percent specifically for Canadian imports of the metals, a plan he later appeared to walk back.

Those threats, however, roiled relations between the US and its northern neighbour in particular. Canada is the top supplier of steel to the US, followed by Brazil and then Mexico. South Korea and China also top the list.

Canada is also responsible for about 40 percent of aluminium imports to the US, followed by the UAE, Russia and Mexico. Carney’s government has pledged to pursue retaliatory measures so long as Trump’s tariffs remain in place.

On Wednesday, one of Canada’s largest labour unions, Unifor, called on Carney to take immediate action against the latest tariff hike, including by limiting the country’s exports of critical metals to the US.

“Unifor is urging the federal government to act without delay to defend Canada’s manufacturing sector and counter the escalating trade assault,” the union said in a statement.

Premier Doug Ford — who leads the top manufacturing province in Canada, Ontario — also called for Canada to respond in kind and “slap another 25 percent” on US steel imports.

“It’s tariff for tariff, dollar for dollar. We need to tariff the steel coming into Canada an additional 25 percent, totalling 50 percent,” Ford told reporters. “Everything’s on the table right now.”

Navigating global trade pacts

Both Canada and Mexico have been hard hit by Trump’s aggressive tariffs, which include a blanket 25-percent tax on all imports not subject to the US-Mexico-Canada free trade agreement (USMCA), as well as a separate 25-percent levy on automobile imports.

The three countries have highly integrated economies, with products like automobiles being built using supplies and factories from multiple locations.

The USMCA pact was agreed upon during Trump’s first term, from 2017 to 2021. But he has since signalled he hopes to renegotiate the free-trade deal to get more favourable terms for the US.

But the doubling of the US steel and aluminium tariffs is expected to have a global impact, well beyond North America.

The European Union is also bracing for the increase. The bloc’s trade commissioner, Maros Sefcovic, met US Trade Representative Jamieson Greer on the sidelines of a meeting for the Organisation for Economic Cooperation and Development (OECD) on Wednesday.

“We’re advancing in the right direction at pace – and staying in close contact to maintain the momentum,” Sefcovic wrote on X afterwards.

UK Trade Secretary Jonathan Reynolds also met with Greer, and he said steel and aluminium tariffs would remain at 25 percent for his country. The two countries have been in the process of forging a post-Brexit bilateral trade agreement, announcing a “breakthrough” last month.

“We’re pleased that as a result of our agreement with the US, UK steel will not be subject to these additional tariffs,” a British government spokesperson said.

‘Extremely hard to make a deal’

Trump’s latest tariff hike comes days after a federal court ruled that his so-called reciprocal tariffs — which imposed customised taxes on nearly all US trading partners — were illegal.

Trump had imposed those tariffs in April, only to pause them for 90 days. The court’s ruling was quickly paused while legal proceedings continued, and Trump’s tariffs have been allowed to remain in place for now.

One of the hardest hit countries has been China, which saw US tariffs against its exports skyrocket to 145 percent earlier this year.

The Trump administration, however, has since sought to reach a deal with China to end the trade war between the world’s two largest economies.

The White House said on Monday that Trump would speak to Chinese President Xi Jinping this week, raising hopes the duo could soothe tensions and speed up negotiations.

But on Wednesday, Trump appeared to dampen hopes for a quick deal.

“I like President XI of China, always have, and always will, but he is VERY TOUGH, AND EXTREMELY HARD TO MAKE A DEAL WITH!!!” he posted on his Truth Social platform.

When asked about the remarks during a regular news briefing, Chinese Foreign Ministry spokesperson Lin Jian said Beijing’s “principles and stance on developing Sino-US relations are consistent”.