It’s been an eventful couple of weeks in AUKUS submarine land. The event that made the biggest splash, at least in Australia, was the United States’ announcement that Under Secretary for Defense Policy Elbridge Colby would lead a review of AUKUS ‘to ensure it aligns with Donald Trump’s “America first” agenda’.

The fact that this announcement and commentary around its implications for Australia’s ‘optimal pathway’ towards its planned nuclear-powered submarine capability has dominated the Australian news cycle for a whole day illustrates the interest, indeed fascination, that Australians have developed in submarines in general and nuclear-powered submarines in particular. But being interested in something doesn’t mean you’ll actually get it.

There appear to be three drivers behind the review. The first is the general Trump ‘vibe’: anything President Joe Biden did was hopeless and AUKUS is a Biden initiative. Therefore AUKUS supporters in the Trump administration will need to convince the president that there is some salvageable goodness there and that he can build on it by getting the Australians to agree to a great deal—great, that is for America. That is after all the declared point of the review, although one of the lessons the world has learned from Donald Trump is that we shouldn’t always (often?)  take him at face value.

The second is the unavoidable fact that providing Australia with US Navy Virginia-class submarines under the so-called ‘optimal pathway’ will result in a decrease in the US Navy’s own capability. Colby has already publicly expressed his concerns about this. Nothing that has occurred since AUKUS was announced will result in there being more Virginias in existence in 2032 than there would have been under the USN’s pre-AUKUS plan.

(Editor’s note: the UK and US submarine challenges were assessed by SAA back in December 2023 – see  ‘Awkward truths about US and UK AUKUS challenges’ . They’re worse now.)

The US Congressional Budget Office has assessed that the negative capability impact on the US Navy will endure throughout the 2030s and potentially into the 2040s.

Moreover, senior US officials and analysts have stated an expectation that submarines transferred to Australia will be used to support the US in any future conflict with China over Taiwan. Australia has consistently refused to provide any kind of guarantee or commitment it would use the submarines that way. To do so would be a major policy departure and would also undermine the Albanese government’s efforts to ‘reset’ relations with our largest trading power.

Finally, there is the percentage of GDP discussion. Even under the Biden administration, the US was signalling dissatisfaction with underwriting the security of allies who were not making adequate contributions to mutual security. The Trump administration has made it very clear that it expects its partners and allies to spend a similar amount of GDP on defence as the US does, which is 3.5%. Hegseth and other officials have made this point very strongly to NATO and are now making the same point to allies in the Indo-Pacific.

The media has widely reported that Hegseth told Australian Minister for Defence Richard Marles that the US wanted Australia to spend 3.5% of GDP on defence. However, Prime Minister Albanese has curtly rejected that call saying that Australia will decide what it spends and suggesting it is foolish to set percentages of GDP as spending targets.

Such push back may play well to Albanese’s Australian political base, but it won’t play well in Washington. The US can legitimately see itself as sacrificing its own naval capability to help Australia while Australia won’t make any sacrifices of its own in the form of greater defence spending.

So what will be the outcome of the review be? As usual claims from both ends of the spectrum on AUKUS are overstated. Marles has said that this is purely routine, perfectly natural, the sort of thing that all incoming governments do. If that is the case, why was it announced a week after Albanese rebuffed the US appeal for greater Australian defence spending? Nor is it likely to be the end of AUKUS as some opponents of the partnership have suggested. It seems unlikely, at this point at least, that the US will just walk away from it.

But this isn’t a simple tick the boxes exercise. Marles claim that this is just like Australia’s 2023 Defence Strategic Review and the United Kingdom’s review of AUKUS doesn’t hold water; both of those exercises started with the writing directions that AUKUS was hard baked into future plans – the UK review, for example, was all about how to help the UK ‘maximise the benefits of AUKUS and unlock further opportunities’, not about giving the megaproject itself a good hard look.

It’s entirely possible that Colby’s review may result in some actual outcomes. Larger Australian financial contributions to the US submarine industrial base (SIB) are one possibility. Or it could tweak the optimal pathway, for example, by locking in milestones that Australia has to meet by particular dates, otherwise the delivery date for Virginias could move to the right. That would actually be a win for AUKUS supporters by requiring greater Australian commitment and focus if it actually wants this capability.

Whatever the immediate outcomes, we shouldn’t expect the review to settle for all time the issue of whether and when Australia will receive Virginias. Any analysis of the challenges the US SIB faces makes that clear. Independent entities such as the US Congressional Research Service have done such analysis. In a nutshell, after the Cold War, the US SIB sank to producing one Virgina per year, a throughput of around 7,800 tonnes of submarine per year. It now needs to produce 2.3 Virginias per year (noting that the block currently under production are over 10,000 tonnes) to meet the USN requirements while transferring 3-5 boats to Australia, requiring a throughput of over 20,000 tonnes per year.

It is also producing the Columbia class SSBNs, which are 20,800 tonnes each. Over the twenty-year life of that program, it averages out to around 12,500 tonnes per year. Essentially that means the pipeline needs to be big enough to pump out over 30,000 tonnes of submarine per year. In other words, that’s around 280% growth from where it was.

Unfortunately, despite the US’s US$9 billion investment in the SIB since 2018, the dial has barely moved on submarine production. In its most recent assessment of the Virginia program, the US Government Accountability Office wrote: ‘The program’s 2024 construction rate fell to 1.15 submarines per year from 1.2 per year in 2023, short of the Navy’s goal of 1.5.’ So it’s short of where it planned to be now and even further short of where it needs to be to be at 2.3 Virginias per year.

Now AUKUS is at its heart a political undertaking. So a US president may well decide to provide Australia with Virginias regardless of the number the USN ultimately has in the early 2030s in the interests of the alliance and other political factors. But that president would have to deal with the awkward issue that according to US legislation the president has to certify to Congress that such a transfer won’t impact USN capability. In an age of ‘America first,’ it’s hard to wish that away. Indeed, by conducting this review, Colby is considering in a proactive way that legislated requirement. However, a review can’t simply wish away the facts on the ground.

That brief review of the pressures on the US’s SIB brings us to the second recent development, namely the release of the UK’s Strategic Defence Review. There’s a lot of be said about the SDR, including its almost eerie parallels with Australia’s 2023 Defence Strategic Review that go well beyond using the same three words in the title. Like the DSR it also began with a pre-determined funding envelop (currently 2.3% growing in the short term to 2.5% and then 3.0% at some undetermined point in the future when the financial and economic circumstances permit), somewhat undermining Albanese’s view that it is foolish to start defence planning with a funding envelop.

But one assessment stands out, namely that ‘a focus on “exquisite” capabilities has masked the “hollowing out” of the Armed Forces’ warfighting capability.’ The reason it stands out is that the SDR also said that the Royal Navy’s SSN fleet should be expanded from seven to ‘up to 12 boats’. That’s striking considering that AUKUS advocates freely extol the fact that nuclear-powered submarines are the most complex machines know to humankind, which one would imagine also makes them among the most exquisite capabilities known to humankind.

Whether a vague commitment to 3.0% of GDP will be enough for a larger SSN fleet without further ‘hollowing out’ of the armed forces is an issue for another time. What we can see, however, is that the UK’s SIB has to climb an even greater growth trajectory than the US’s.

The UK was building one 7,200 tonne Astute every three years, for an average throughput of 2,400 tonnes. The SDR said that will accelerate to one SSN-AUKUS every 1.5 years. SSN-AUKUS will also be a much bigger boat at over 10,000 tonnes.

In addition, the UK will be supporting Australia’s own SSN-AUKUS build. If we assume that Australia’s delivery drumbeat will be one boat every three years, the combined enterprise has to deliver three 10,000 boats every three years for an average of 10,000 tonnes per year, four times as much as where the UK SIB had been. While Australia brings some industrial capacity to the show, it is still reliant on the UK for key components such as the reactors and other parts of the propulsion.

However, like the US, the UK is also now building its next generation of SSBN, the Dreadnought. These are 17,200 tonnes with a four-yearly drumbeat, adding a further 4,300 tonnes to the annual pipeline. Overall, the pipeline needs to grow to around 14,000 tonnes per year, or by around 500% from where the UK SIB has been.

So whether we are talking about Virginia’s or SSN-AUKUS, Australia is a junior partner in a highly dependent relationship with a senior partner that will likely be hard pressed to meet its own requirements. That’s not going to change anytime soon.

Advocates of AUKUS like to state that the enterprise is on track. It’s impossible to validate that since the Australian government has not provided any kind of roadmap for the development of the necessary elements of that capability with the milestones that need to be met. What we can say is that almost four years into the AUKUS submarine enterprise, none of the key risks around the have yet been retired. One of the greatest of those risks is the ability of the partner countries to scale up their respective SIBs.

Again, that doesn’t mean Australia won’t develop an SSN capability, but whatever the outcomes of Colby’s review, uncertainties will remain. No review can magically transform the facts on the ground in shipyards and reactor factories.