While Mr Trump signed off on 25 per cent tariffs without exception, his suggestion he is considering giving Australia a pass has provided hope for workers dependent on the industries for their livelihood.
In Portland, on Victoria's southwest coast, the local aluminium smelter directly employs about 600 workers and just as many contractors in a town of 10,000.
"The importance of the smelter to us, to the local economy, is just huge," Glenelg Shire mayor Karen Stephens told AAP.
"This just throws that spanner in the works and gives that uncertainty."
Australia's aluminium and steel industries support more than 175,000 jobs and contribute $47 billion to the national economy each year.
BlueScope is the only Australian steel producer with substantial exports to the US, according to the Australian Steel Institute.
However, fears other nations will dump cheaper products in Australia could have a big impact on the entire local sector.
Communities in the Georgetown area of northern Tasmania are likely exposed to the tariff threat more than most, according to Mayor Greg Keiser.
Two smelters at Bell Bay, which make aluminium and manganese used in steel, are the two biggest businesses in the council area.
"Obviously, the one that we're most concerned about would be direct employment," Mr Keiser told AAP.
He estimates 30 per cent of smelter workers live in his municipality of 7500 people and believes most are apprehensive Australia can secure an exemption as it did in Mr Trump's first term.
The small rural community was familiar with riding the swings and roundabouts of the global markets.
"We've been down the road before, even though this has a different look and feel to it," Mr Keiser said.
ACTU President Michele O'Neil is concerned about the impact on wages and conditions of highly skilled workers who have been at the same companies for generations.
"They importantly support the economy of these regions as well," she said.
"So there's a flow on effect to other contractors, other businesses that rely on the manufacturers of steel and aluminium."
The direct and indirect effects may be unclear until the tariffs are implemented, said Business Hunter chief executive Bob Hawes.
The peak business group in NSW's Hunter region is home to Australia's biggest aluminium smelter at Tomago.
"So a lot of uncertainty is a consequence, which is not a good thing for business or governments for that matter," Mr Hawes told AAP.
There could even be positives for certain product suppliers, depending on how trading partners reacted to Mr Trump's tariffs, Mr Hawes said.
"We just have to get on with it, and hopefully not too many of our businesses suffer as a consequence."
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