Donald Trump has threatened extraordinary new taxes onone of Australia's biggest exports to the US.

The US president said he was looking to announce 200 per cent tariffs on all imported pharmaceuticals.

"If they have to bring the pharmaceuticals into the country... they're going to be tariffed at a very, very high rate, like 200 per cent."

"We'll give them a certain period of time to get their act together."

The tariffs would make Australian-made vaccines and drugs far more expensive for Americans to buy.

Pharmaceuticals are Australia's second biggest export to the US, behind beef.

According to the Observatory of Economic Complexity, vaccines, antisera, toxins and cultures are worth more than $1.6 billion each year.

Much of this comes from one company, Melbourne-based CSL, which manufactures flu shots, among other pharmaceuticals.

Internationally, the pharmaceutical tariffs will hit Ireland and Germany the hardest.

Trump's tariff threat comes as he announced a new tariff on copper.

While Australia is a major copper exporter, very little of it goes to the United States.

Most of Australia's copper exports go to Japan, the Philippines, South Korea and India.

"Our exports of copper to the US are actually quite small," Treasurer Jim Chalmers told ABC Radio National.

"Our pharmaceuticals industry is much more exposed to the US market, and that's why we're urgently seeking some more detail on what's been announced."

Copper futures prices surged more than 10 per cent in the moments after Trump announced his new tariffs.

Trump's so-called Liberation Day tariffs were supposed to take effect today.

But yesterday the president announced the implementation would be pushed back to August 1.

Chalmers decried Trump's tariff plan at a press conference yesterday.

"We've made it very clear that we think these tariffs are bad for the US, bad for Australia and bad for the global economy," he said.

Wall Street ended the day mixed, with the S&P 500 dropping slightly the day after a massive drop.

What do we sell to America?

Australia's exports are largely raw materials, measured by the tonne.

But the US is selling finished products, where single items cost thousands of dollars.

The most valuable Australian export is beef, either frozen or fresh.

Australia sold about $2.7 billion worth of beef to the US in 2023, much of it going to McDonald's.

Lamb and goat accounted for another $1.4 billion.

Australia's second most valuable export to the US is vaccines and other pharmaceuticals.