US President Donald Trump says he will announce tariffs on all steel and aluminium imports to the US, as he reshapes America’s trading relationship with the world.

The move could have a particular impact on neighbouring Canada, which is the biggest supplier of aluminium to the US. Trump has also threatened to introduce tariffs at a later date on other products from Canada, as well as Mexico.

He has already introduced a levy of 10% on all products entering from China – which has responded with its own measures.

The US president says these import taxes are needed to help the US economy and to “protect” the country from illegal immigration and the flow of drugs. Economists say they could push up prices for Americans.

Tariffs are taxes charged on goods imported from other countries.

Companies that import goods from abroad pay the tariffs to the US government.

Trump has introduced a 10% tariff on all goods from China. So, a product worth $10 would have an additional $1 charge applied to it.

The president originally said he would impose a 25% tariff on goods from Canada and Mexico, but later agreed to pause these after both countries agreed to boost border security.

Charging a percentage of a product’s value is the most common type of tariff. Another type imposes a fixed figure on imports, whatever their value.

Trump is fulfilling a campaign promise of introducing import duties against some of America’s closest trading partners.

He argues that tariffs will boost US manufacturing and protect jobs – for example in the US steel industry – as well as raising tax revenue and growing the economy.

He has also sought to justify tariffs on metals – which he also introduced during his first term – as a national security issue.

Trump also says he is using tariffs to “combat the scourge of fentanyl”, a powerful drug that causes tens of thousands of overdose deaths in the US each year.

His administration says chemicals used to make the drug come from China, while Mexican gangs supply it illegally and have fentanyl labs in Canada.

Canadian Prime Minister Justin Trudeau has said less than 1% of fentanyl entering the US comes from his country.

Together, China, Mexico and Canada accounted for more than 40% of imports into the US last year, making them some of Trump’s most valuable trade partners.

China

A 10% charge on all goods imported from China to the US took effect on 4 February.

Beijing retaliated with its own tariffs that took effect on 10 February. These include a 15% tariff on US coal and liquefied natural gas products, and a 10% tariff on crude oil, agricultural machinery and large engine cars.

China has repeatedly voiced its opposition to a new trade war of the kind that developed between the two countries during Trump’s first presidency.

Canada

Trump paused for 30 days a proposed tariff of 25% on all goods entering from Canada – which was also due to begin on 4 February.

Canada also paused its own retaliatory tariff of 25% on 155bn Canadian dollars’ worth ($107bn; £86bn) of US imports.

In exchange for Trump’s pause, Canadian Prime Minister Justin Trudeau said Canada was implementing a “$1.3bn border plan” to add “new choppers, technology and personnel to border,” as well as “increased resources to stop the flow of fentanyl”.

Much of the border security plan had already been announced in December.

Trump said the delay would allow the US to see “whether or not a final economic deal with Canada” could be reached.

Mexico

The proposed 25% tariffs against Mexico have also been delayed a month, as have measures by Mexico against US goods.

Mexico’s President Claudia Sheinbaum agreed to send 10,000 members of the National Guard to the US-Mexican border to “prevent the trafficking of drugs, in particular fentanyl”.

President Sheinbaum said the US had in turn agreed to increase measures to prevent the trafficking of high-powered US weapons into Mexico.

During Trump’s previous time in office, he applied less restrictive tariffs on China. This time around, the tariffs appear to apply to all goods from China.

If the measures against goods from Mexico and Canada ultimately go ahead, a range of items are expected to become more expensive.

Car manufacturing could bear the brunt of the effects of tariffs.

Vehicle parts cross the US, Mexican and Canadian borders multiple times before a vehicle is completely assembled.

The average US car price could increase by $3,000 because of the import taxes, financial analyst TD economics suggested.

Other goods from Mexico which could be affected include fruit, vegetables, spirits and beer.

Canadian goods such as steel, lumber, grains and potatoes would also be likely to get pricier for US consumers.

Canadian energy would be tariffed at 10% instead of 25%.

Trump previously told the BBC the UK was acting “out of line”, without giving further detail, but suggested a solution could be “worked out”.

The UK’s business secretary, Jonathan Reynolds, said the UK should be excluded from tariffs because the US exports more products to the UK than it imports.

The UK exports pharmaceutical products, cars and scientific instruments to the US.

Trump has also said he could impose tariffs on the EU “pretty soon”, because “they take almost nothing [from the US] and we take everything from them”.

Last year, the US had a trade deficit of $213bn with the EU – which Trump described as “an atrocity”.

The EU has said it would “respond firmly” to any tariffs. US companies Harley Davidson, which manufactures motorcycles, and whiskey distilleries such as Jack Daniel’s have previously faced EU tariffs.

Economists have warned that tariffs are likely to raise prices for US consumers.

For example, sellers may raise the price of goods they are importing if they are forced to pay higher duties.

From 2018 to 2023, tariffs on imported washing machines saw the price of laundry equipment rise by 34%, according to official statistics, before falling once the tariffs expired.

Some experts suggest that these new tariffs could prompt a wider trade war and exacerbate inflation.

Capitol Economics has said the annual rate of inflation could increase from 2.9% to as high as 4% because of the newly announced tariffs.