Trump signs executive orders on steel, aluminum tariffs

US President Donald Trump has signed executive orders to slap 25% tariffs on steel and aluminum imports, stepping up a long-promised trade war despite warnings from Europe and China.

"Today I'm simplifying our tariffs on steel and aluminum," Trump said in the Oval Office as he signed executive orders. "It's 25% without exceptions or exemptions."

Trump also signaled that he would look at imposing additional tariffs on automobiles, pharmaceuticals and computer chips.

Canada and Mexico -- which Trump has already threatened with tariffs -- are the biggest steel importers to the United States, according to US trade data. Brazil and South Korea are also major steel providers.

The US leader 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 Trump signed the documents, Australian Prime Minister Anthony Albanese said an exemption was on the table, after speaking with Trump.

"The US president agreed that an exemption was under consideration in the interests of both of our countries," Albanese told reporters after the call.

Trump imposed sweeping tariffs during his 2017-2021 presidency to protect US industries, which he believed faced unfair competition from Asian and European countries.