This time next year American and British nuclear-powered submarines are expected to be operating out of Perth’s HMAS Stirling naval base, but as the deployments fast approach, frustrations are building between AUKUS partners.

Under this country’s optimal pathway for acquiring the nuclear-powered technology, up to four US boats and one British boat will first be based in WA from 2027 as part of Submarine Rotational Force-West (SRF-West).

Then in the 2030s the US is scheduled to begin selling second-hand Virginia-class submarines to Australia. However last week the top AUKUS sceptic in the Trump administration stopped short of guaranteeing the on-time delivery.

During a tour of southeast Asia last week, Pentagon official Elbridge Colby declared Washington was “optimistic” but “clear-eyed” about what was needed to be done to lift the production rates of Virginia-class submarines so boats can be sold to Australia.

Repeating President Donald Trump’s declaration last year that AUKUS was “full steam ahead”, the Under Secretary said there was a “very clear understanding” between partner nations on what was needed to deliver nuclear-powered submarines to Australia.

Tellingly, the Under Secretary for War did not directly answer when asked about the current production rate of Virginia-class nuclear submarines, which is languishing at about one to 1.2 boats a year, but needs to reach 2.33 to meet AUKUS requirements.

“We all know this is a historic endeavour on the part of both countries, but particularly for Australia, and that requires a real level of effort that we see the evidence for, and so we remain optimistic, but also clear-eyed, about what we all need to do to achieve that,” Mr Colby said.

“Obviously, there’s a lot of things that the Australian side needs to do. They know what is required.”

What also did not go unnoticed in Canberra was that despite travelling from Washington to southeast Asia, Colby choose not to fly a little further and visit Australia.

The Pentagon policy chief is not the only high-ranking Trump administration figure to hold concerns about AUKUS’s progress, even if those views are for now largely being expressed in private.

Just last month US officials were sent scrambling for urgent assurances from the Albanese Government over SRF-West after Defence Industry Minister Pat Conroy suggested the arrangement would be limited to five years.

Privately, US officials are also alarmed at the protection levels of Australian bases, including HMAS Stirling and RAAF Base Darwin, where significant numbers of US personnel and military assets will be operating.

Earlier this month a conservative and influential Trump-aligned think tank urged Australia to spend billions buying US-made missile interceptors to defend key bases from Chinese military attack.

“At least three THAAD batteries and hundreds of interceptors to defend key bases, such as RAAF Base Darwin, from PLA attack, reducing the inventory and cost burden on U.S. inventories of scarce munitions and enhancing Australia’s ability to defend itself,” the Heritage Foundation’s Jim Fein recommended.

The Heritage Foundation report also called for the US Congress, Australia and Japan to fund “additional Indo–Pacific infrastructure improvements to harden them against ballistic missile attack, especially intermediate-range ballistic missiles”.

Next week Anthony Albanese is scheduled to fly to Western Australia where anticipation is growing of a long-awaited announcement on the revamped Henderson shipyard, which is being overhauled to help support nuclear-powered submarines.

Figures close to the redevelopment of the new Henderson Defence Precinct believe a deal is almost finalised with the WA Government on a land swap agreement for a new Common User Facility to be used by naval shipbuilders.

This week, the British Minister for Defence Readiness and Industry Luke Pollard toured the Henderson site and declared WA “is the right location for an enterprise on this scale”.

“It has the skilled workforce, the industrial capacity, and the supply chain that AUKUS requires,” Pollard told The West.

“Just as importantly, it has the trusted relationships needed to integrate sensitive and sophisticated technologies at scale, something that cannot be built overnight.”

In the final stage of the AUKUS optimal pathway, Australia will jointly work with the United Kingdom to build a new fleet of nuclear-powered submarines in Adelaide called SSN-AUKUS, that is expected to be delivered in the 2040s.

For some defence industry observers, there has been far more tangible progress getting Adelaide’s Osborne shipyard ready for its massive task, than the more immediate and pressing need to get Henderson ready to support AUKUS submarines in the 2030s.