The Turnbull government isn't giving up hope US President Donald Trump could exempt Australia from new steel and aluminium tariffs.
But exporters have been assured Australia is focused on other markets should the worst case scenario occur.
Mr Trump wants to impose a controversial 25 per cent tariff on steel imports and 10 per cent on aluminium, which Labor leader Bill Shorten described as triggering a "trade war".
Australia, Canada, European nations and other allies were hoping to be exempt, but White House trade adviser Peter Navarro confirmed on Sunday Mr Trump's tariffs would be "across the board".
Trade Minister Steve Ciobo will join his counterparts from 10 countries for the Trans-Pacific Partnership signing ceremony in Chile on Thursday and expects the US action to be discussed on the sidelines.
"The value of the TPP 11 is reinforced by the US tariff decision ... it's about ensuring we diversify Australia's export markets to safeguard the future of our exporters," Mr Ciobo told AAP on Monday.
Prime Minister Malcolm Turnbull received assurances about exemptions from the US at the G20 summit in Germany last year.
Mr Ciobo followed up with his American counterpart on Saturday, but said afterwards it appeared details of the new imposts were still being worked out and ultimately any exemptions would be a decision for Mr Trump.
"I'm not going to provide a commentary on the Trump administration's trustworthiness," Mr Ciobo said.
Fellow cabinet minister Christopher Pyne said the government continued to work with the US on details of the arrangement.
Former Labor foreign minister Bob Carr believes despite the tough talk from the White House, Australia will wind up with an exemption.
"Embassy sources assure me that when small print comes out Oz steel will be exempted from tariff hikes," he tweeted, saying it would acknowledge the "100 years of mateship" celebrated during Mr Turnbull's visit and the "persuasive presence" of a huge Australian business delegation.
Mr Shorten said Mr Turnbull should get on the phone to Mr Trump to fight for Australia's steel and aluminium industries.
"I want to know what Mr Turnbull's doing to protect tens of thousands of fair dinkum everyday jobs," Mr Shorten told reporters in Perth.
The Labor leader said the president's "trade war" was a dangerous path which could see the steel industry "hit for six".
About 400,000 tonnes of steel a year is exported into the US from Australia.
The US market is worth about $274 million for steel and $276 million for aluminium, in terms of Australian exports.
But it is the potential for a wider escalation of a trade war across more sectors and markets that has industry concerned.
Modelling by Deloitte Access Economics shows a global trade war could cut $5 billion from national income and cost 20,000 Australian jobs, the Australian Financial Review reported.
Apart from the impact on exporters, there are also fears the domestic steel industry could be at risk from cheap products being dumped on the Australian market if access to the US is curtailed.
Labor says the anti-dumping commission must be on high alert.
