WASHINGTON, United States (AFP) — Mounting trade wars between the US and its largest economic partners deepened on Tuesday as its tariffs on Canada, Mexico and China kicked in, sparking swift retaliation from Beijing and Ottawa.

Stinging US tariffs on Canadian and Mexican goods came into effect as a deadline to avert President Donald Trump’s levies passed without the nations striking a deal — a move set to snarl supply chains.

Trade war fears sent markets falling in Asia and Europe on Tuesday in response to what analysts said were its steepest tariffs on imports since the 1940s.

Trump had announced — and then paused — the blanket 25 percent tariffs on imports from major trading partners Canada and Mexico in February, accusing them of failing to stop illegal immigration and drug trafficking.

In pushing ahead with the duties, Trump cited a lack of progress in tackling the flow of drugs like fentanyl into the US.

The duties stand to impact over $918 billion worth of US imports from both countries.

The sweeping duties on Canada and Mexico are set to snarl supply chains for key sectors like automobiles and construction materials, risking cost increases to households.

Mexico supplied 63 percent of US vegetable imports and nearly half of US fruit and nut imports in 2023, according to the US Department of Agriculture.

More than 80 percent of US avocados come from Mexico — meaning higher import costs could push up prices for American shoppers.

And the US imports construction materials from Canada, too, meaning tariffs could drive up housing costs.

More than 70 percent of imports of two key materials homebuilders need — softwood lumber and gypsum — come from Canada and Mexico, said National Association of Home Builders chairman Carl Harris.

Trump also inked an order Monday to increase a previously imposed 10 percent tariff on China to 20 percent — piling atop existing levies on various Chinese goods.

Beijing condemned the “unilateral imposition of tariffs by the US” and swiftly retaliated, saying it would impose 10 and 15 percent levies on a range of agricultural imports from the US.

China’s tariffs will come into effect next week and will impact tens of billions of dollars in imports, from US soybeans to chickens.

Beijing’s foreign ministry vowed to fight a US trade war to the “bitter end.”

“The Chinese people will not be intimidated,” spokesperson Lin Jian said.