Australia's ambassador to the US, Arthur Sinodinos, says the two countries have intensified efforts to unwind US technology export restrictions that could ensnare the AUKUS agreement and frustrate Australia's push for nuclear-powered submarines.

The US has committed to sharing nuclear propulsion technology with Australia under the tripartite agreement with the United Kingdom.

All three countries have also agreed to work together more closely to share and develop cutting-edge military technology across a range of fields ranging from hypersonic missiles to cyber technology.

But US defence technology remains tightly controlled under International Traffic in Arms regulations and other restrictions.

Some US bureaucrats have also expressed concerns that America's military adversaries may also find it easier to steal classified military technology and sophisticated intellectual property from within the Australian system.

Mr Sinodinos told the Washington-based Centre for Strategic and International Studies (CSIS) that Australia had "assured the Americans and shown them the sort of protection-of-information measures we take, to make sure we understand their technology is safe in terms of leakage to third parties".

He also said the Biden administration and the US Congress were keenly aware that defence transfer restrictions would have to be unwound for AUKUS to function effectively.

"Various organisations within the administration are thinking about what are the tools at the working level that we can adopt to make it easier for us to work together and get [that] sort of seamless transfer of technology," he said.

"That work is underway; it's not finished, but compared with say six months ago, the work is getting done."

US 'to share their crown jewels'

Some Australian officials have publicly acknowledged that cumbersome bureaucratic hurdles in all three countries could threaten cooperation under AUKUS, particularly in the "second pillar" talks on high-level defence technology.

According to Reuters, Stephen Moore from Australia's Department of Defence said yesterday there was "frustration" about information sharing among AUKUS partners, and a recognition that "our bureaucratic processes need to be better".

Mr Sinodinos said both senior officials in the Biden administration and members of the US Congress were looking at the best way to ensure technology could flow more freely to Australia.

"The Congress is looking at ways which, for example, they might use the National Defense Authorisation Act every year as a way to continue to progress some of this," he said.

"But I think it's fair to say at the moment the Congress is also waiting to see how far the administration is prepared to go."

Mr Sinodinos said the Biden administration was trying to give mid-level bureaucrats the "tools" they needed to break down barriers.

"This is what we have always been trying to do, to get the frozen middle, if you like, to start to thaw and start to think about the trilateral way the US and Australia and the UK can work together on this," he said.

"The very fact that the Americans are prepared to share their crown jewels with us implies that there will have to be progress on the seamless transfer of technology. None of us want this to be bogged down.

"And I think that state of mind has now permeated through various levels of the [US] administration."

Allies are 'comparative advantage' for US in Indo-Pacific

Ashley Townshend from Carnegie Endowment for International Peace said Mr Sinodinos was pushing for a cultural shift within key United States government departments.

"The frozen middle are the mid-level bureaucrats, particularly in the State Department, who are duty-bound to preserve – and personally liable to enforce – restrictive information-sharing and export control regulations designed to protect, and ultimately limit, the flow of US defence technology and technical know-how," he said.