Mounting trade wars between the United States and its largest economic partners deepened yesterday as huge US tariffs on Canada, Mexico and China kicked in, sparking swift retaliation from Beijing and Ottawa.

Markets fell in Asia and Europe in response to what analysts said were the steepest tariffs on imports since the 1940s.

Trump had announced -- and then paused -- 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.

He pushed ahead with them yesterday, citing a lack of progress on both fronts.

The duties will hit over $918 billion in US imports from both countries, and are set to hamper supply chains for key sectors like automobiles and construction materials.

Canada responded with its own retaliatory 25 percent tariffs, while Mexican President Claudia Sheinbaum said there was no justification for the US move and vowed to hit back with duties of its own.

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 said it would impose 10 and 15 percent levies on a range of agricultural imports from the United States.

Experts have warned the higher import costs could push up prices for consumers, complicating efforts to bring down inflation.

That includes at grocery stores -- 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.

Housing costs could also be hit. More than 70 percent of imports of two key materials homebuilders need -- softwood lumber and gypsum -- come from Canada and Mexico, said the National Association of Home Builders.

Truck drivers at the Otay Mesa border crossing in Mexico told AFP they were already feeling the impact as they waited to cross into the United States early yesterday.

Work was drying up because many companies in the Mexican border city of Tijuana export Chinese goods, said driver Angel Cervantes.

"And since the tariffs are also against China, work is going down for the (transport) companies," he added.