The Morrison government stands by its level of defence spending and the importance of the US, in the wake of a new book questioning both policies.
Australia is pulling its weight in terms of defence spending and America remains a "fundamental ally", Treasurer Josh Frydenberg says.
Security analyst and Australian National University professor Hugh White has, in a new book, suggested it's now less clear that Australia can rely on the US to defend it.
That means Australia might need to consider getting its own nuclear weapons to defend itself amid the rise of China, he has argued, and spend an extra $30 billion on defence.
Mr Frydenberg said America was a "fundamental ally" of Australia and the ANZUS alliance was essential to the nation's security.
"At the same time, we're investing even more in our defence forces, bringing it back to two per cent of GDP compared to the 1.6 per cent which was under Labor, which was the lowest defence funding since the time of appeasement back in 1938," Mr Frydenberg told the ABC's AM program on Tuesday.
Labor defence spokesman Richard Marles said Australia should not seek out nuclear weapons, given it's a signatory to the long standing Treaty on the Non-Proliferation of Nuclear Weapons.
Instead, it should consider better expressing the "leadership side" of its international personality, he believes.
"[That's] something that I don't think we've been particularly comfortable doing up until now," he told ABC Radio Melbourne.
He said Australia's relationship with the US is as important as ever and Australia should encourage them to stay engaged in the Asia Pacific, he said.
"They've got our back to the extent that that America is present and we need to be doing everything we can to argue for an influence of America in maintaining its presence."
The comments came as the new US ambassador Arthur Culvahouse said Australia could rely on his country if it came under threat.
"I come out here well instructed after a series of consultations at the highest levels of the United States government, and our commitments are solemn and unbreakable and profound," he told The Australian.