Foreign Minister Julie Bishop insists the Trump administration expects any new military co-operation after granting Australia exemptions from hefty tariffs.
Turnbull government ministers are adamant the United States does not expect anything from Australia in return for exempting Aussie steel and aluminium from new tariffs.
US President Donald Trump said in a tweet his administration was "working very quickly on a security agreement so we don't have to impose steel or aluminum (sic) tariffs on our ally, the great nation of Australia".
Questions have been raised over what such a security agreement might entail, especially in light of Mr Trump telling the prime minister in February he would love Australia to join the US on new freedom of navigation exercises in the South China Sea.
But Foreign Minister Julie Bishop is emphatic there is no new security or military arrangement Australia is expected to meet.
Mr Trump's reference to a "security agreement" was just using the specific language of the executive order he issued on the tariffs, she said.
"There is no further security arrangement. There was no reciprocal arrangement as a result of the tariff exemption," she told reporters in Adelaide on Sunday.
"The exemption is simply an exemption based on what they call national security grounds ...The United States was not asking anything in return."
Trade Minister Steve Ciobo also denied any quid pro quo was expected.
"I've seen some, frankly, incredibly wild theories emanating from all quarters including some journalists who should know better," he told ABC TV.
"It is effectively just about the paperwork."
Mr Trump also lauded Prime Minister Malcolm Turnbull's commitment to "a very fair and reciprocal military and trade relationship", after eight months of Australian ministers and officials putting just this argument to the Trump administration.
Ms Bishop said the Turnbull government first got wind of the possibility of new tariffs in April 2017 and swung into action with a strong lobbying effort by ministers, officials and business contacts.
Labor's finance spokesman Jim Chalmers said it remained to be seen what expectations might be attached to the deal, but Australia did have a long history of co-operation with the US on both economic and military fronts.
"I think a whole range of factors come into these sorts of deals that are made between countries, not just the military one but economic co-operation as well," he told Sky News.
Australia signed a free trade agreement with the US in 2005, under the Howard government.
There is a trade deficit with the US, meaning more American products and services are bought down under than sent the other way.
Recent analysis from CommSec shows that in January that trade deficit was the second largest on record, with an $18.5 billion difference between imports and exports.