US President Donald Trump has moved to substantially raise tariffs on steel and aluminium imports, cancelling exemptions and duty-free quotas for major suppliers Canada, Mexico, Brazil and other countries in a move that could boost the risk of a multi-front trade war.
Mr Trump signed proclamations that raised the tariff rate on aluminium imports to 25% from the previous 10% that he imposed in 2018 to aid the struggling sector.
His action reinstates a 25% tariff on millions of tons of steel imports and aluminium imports that had been entering the US duty free under quota deals, exemptions and thousands of product exclusions.
The proclamations were extensions of Mr Trump's 2018 Section 232 national security tariffs to protect steel and aluminium makers. A White House official said the exemptions had eroded the effectiveness of these measures.

President Trump also will impose a new North American standard requiring steel imports to be "melted and poured" and aluminium to be "smelted and cast" in the region to curb imports of minimally processed Chinese steel into the US.
The order also targets downstream steel products that use imported steel for tariffs.
Mr Trump's trade adviser Peter Navarro said the measures would help US steel and aluminium producers and shore up America's economic and national security.
"The steel and aluminium tariffs 2.0 will put an end to foreign dumping, boost domestic production and secure our steel and aluminium industries as the backbone and pillar industries of America's economic and national security," he told reporters.
"This isn't just about trade. It's about ensuring that America never has to rely on foreign nations for critical industries like steel and aluminium."
President Trump first broached the steel and aluminium action on Sunday, adding that he would also announce a further set of reciprocal tariffs later in the week, drawing warnings of retaliation from trade partners.
Read more: Trump's EU tariff threats raises concern among leaders
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
Donald Trump also confirmed that he was considering an exemption for Australia from the steel tariffs.
"We have a (trade) surplus to Australia, one of the few. And the reason is they buy a lot of airplanes. They are rather far away and need lots of airplanes," he said.
Just before Mr Trump signed the documents, Australian Prime Minister Anthony Albanese said an exemption was on the table, after speaking with Mr Trump.
"The US president agreed that an exemption was under consideration in the interests of both of our countries," Mr Albanese told reporters after the call.
Germany signals EU 'determination' after US tariff move
Germany said Europe would act in a "united and determined manner" in response to the tarrifs.
"In the long term, a tariff conflict only has losers," Robert Habeck, the economy minister and vice chancellor of Europe's biggest economy, said in a statement.
"For Germany and the EU, the most important thing is that we continue on the path of cooperation with the United States, from which both sides benefit.
"But it is also clear that Europe must and can only react to unilateral trade restrictions in a united and determined manner. And we are prepared for that."
France also warned the EU will counter in kind and "replicate" any tariffs imposed on it by the United States. The bloc has said it has not received any official notification yet of the new duties.
A spokesperson for British Prime Minister Keir Starmer said Britain has not seen details of the proposed tariffs and will continue to engage with the Trump administration as appropriate.
Mr Starmer's spokesman said while it was not possible tos peculate on the impact of such tariffs without seeing details, Britain always prepares for all developments.
"I haven't seen any detailed proposals following reporting overnight, but we will obviously engage as appropriate," the spokesman told reporters.
Border steps
In a separate Fox News interview, Mr Trump said Canada's and Mexico's actions to secure their US borders and halt the flow of drugs and migrants are insufficient ahead of a 1 March tariff deadline.
Mr Trump has threatened to impose tariffs of 25% on all Mexican and Canadian imports unless America's two largest trading partners take stronger actions.
He paused the tariffs until 1 March after some initial border security concessions from the two countries, with Mexico pledging to add 10,000 National Guard troops to its border and Canada deploying new technology and personnel and taking new anti-fentanyl steps.

Asked whether Mexico's and Canada's actions were good enough, Mr Trump replied "No, it's not good enough."
"Something has to happen, it's not sustainable, and I'm changing it," he added.
Mr Trump did not say what Canada and Mexico needed to do to avoid broad tariffs on 1 March.
Commitment to 'buying and owning' Gaza
Separately, Mr Trump said he is committed to buying and owning Gaza, but could allow sections of the war-ravaged land to be rebuilt by other states in the Middle East.
"I'm committed to buying and owning Gaza. As far as us rebuilding it, we may give it to other states in the Middle East to build sections of it, other people may do it, through our auspices. But we're committed to owning it, taking it, and making sure that Hamas doesn’t move back.
"There’s nothing to move back into. The place is a demolition site. The remainder will be demolished. Everything’s demolished," he added.
Mr Trump also said he was open to the possibility of allowing some Palestinian refugees into the United States, but would consider such requests on a case-by-case basis.
Ezzat El Rashq, a member of the Hamas political bureau, condemned Mr Trump's latest remarks on buying and owning Gaza, the group said in a statement.
"Gaza is not a property to be sold and bought. It is an integral part of our occupied Palestinian land," and Palestinians will foil displacement plans, Mr Rashq added.
Mr Trump has spoken of permanently displacing Palestinians who live in Gaza and would create a "Riviera of the Middle East."