As we prepare to dive into the depths of the AUKUS submarine “optimal” pathway tomorrow, details have been steadily emerging. This plan presents both opportunities and risks for Australia and its AUKUS partners. It is the most ambitious defence capability plan in Australian history.

The plan, as reported so far, envisages the forward deployment of US and possibly UK submarines to Perth’s HMAS Stirling base in the very near future, and the delivery of nuclear-powered US Virginia-class submarines to solve capability gaps as the current crop of Collins-class Australian conventional submarines come to retirement. That will be followed by the delivery of a new generation of SSN AUKUS nuclear-powered submarines – a model that will be a trilateral UK, US and Australian design, focused around the more advanced US technology. These subs will be built in Adelaide.

The big surprise so far is the indication that Australia could possibly borrow, lease or buy three to five US Virginia-class submarines to fill the looming Collins retirement capability gap

The first development is the forward basing option. This would be a wise option, allowing for the Royal Australian Navy to familiarise itself with the capabilities on offer, improve interoperability and gain valuable experience. Most significantly, this allows for concurrent activity with the massive uplift in infrastructure needed in Western Australia to service and support nuclear-powered submarines (SSN). The big question here is, will we see UK as well as US boats forward deployed, how often will the rotations occur, and how many Australians will be involved in crewing the US and possibly UK boats?

The big surprise so far is the indication that Australia could possibly borrow, lease or buy three to five US Virginia-class submarines to fill the looming Collins retirement capability gap. This has been alluded to numerous times in the last 12 months but seemed one of the least likely options. This is because the US Navy is short of its own attack-class submarines and its shipyards are struggling to meet current requirements without adding demand from Australia.

We know for sure that there will be no interim conventional submarine to fill the gap – this option having been ruled out by Deputy Prime Minister Richard Marles in Paris. The UK has ruled out leasing, selling or loaning its Astute-class SSNs – which are also not desirable as they don’t share a combat system or weapons with the Collins class, unlike US submarines. So by process of elimination the US has to fill the gap – how is the big question.

Getting a loan, lease or buy option for Virginia-class submarines through the US Congress and getting the US Navy fully behind it will not be easy. Once (and if) this hurdle is crossed, the key questions are how will the Royal Australian Navy crew these submarines – given the existing workforce crisis in defence and the much larger complement of the US boats over the current Collins class – and how will Australia gain and maintain full “sovereign control” over their operations and deployments?

The third piece of this puzzle is the domestic build of what is looking more and more likely as a new design: SSN AUKUS. In many ways this makes sense. Both the US and the UK are looking at designing their next generation of attack-class submarines. This presents the opportunity for enormous synergies. A trilateral design involving the US, UK and Australia, especially if all three countries adopted US reactors, combat systems and weapons, would provide both interchangeability and the ability to undertake cost-sharing for ongoing upgrades, maintenance and support. This is especially important as a key driver of AUKUS is to ensure all three countries maintain a capability edge in undersea warfare over any potential adversaries.

While it seems logical for Australia and the UK to build such a boat, the big unknown would be if the US Navy adopts the design or continues with its own program. The holy grail of a true trilateral collaboration would be a common design and build in all three countries and production lines producing submarines in continuous builds across two US yards and one each in Australia and the UK.

The holy grail of a true trilateral collaboration would be a common design and build in all three countries and production lines producing submarines in continuous builds across two US yards and one each in Australia and the UK.

While this plan delivers high-end capability quickly, deals with the capability gap and puts Australia on a clear pathway to a sovereign capability, it’s not without high risk.

First, this plan would potentially see Australia operating three different types of submarines for a period of time – the last of the Collins boats, the interim Virginia class, and the new AUKUS boats. This could prove enormously expensive and difficult in terms of maintenance, sustainment, training and operations.

Second, a new SSN AUKUS design will surely make many capability managers, politicians and pundits very nervous. Defence does not have a strong record in this area and the navy in particular has struggled to maintain design discipline. Constant design changes have slowed projects, frustrated industry and blown out budgets. The current Hunter-class frigate was supposed to bring synergies by sharing the design between the UK, Canada and Australia. But this project has blown out the budget, hit delays and fractured its initial approach as the design has constantly been modified, raising concerns about its viability. Perhaps the trilateral approach may bring more discipline to an SSN AUKUS design, but it also brings potentially very high risk.

Finally, infrastructure and workforce challenges loom large. The timeline for a new design is tight, Australia will have to undertake massive investment in Adelaide to prepare the shipyard to undertake the build. All while defence industry, and the economy more broadly, suffer from workforce shortages. Given the highly sensitive nature of the work, this problem cannot be solved quickly by rapid migration of skilled workers. The potential payoff, though, is huge. If we get it right and take on board the lessons from our partners, Australia could have the newest, most efficient and cost-effective nuclear-powered submarine manufacturing capability in the Western world.

The overarching question that looms large over Tuesday’s announcement is, is it worth it? In defence circles ambitions are often limitless, but resources are always finite. The Albanese government has committed to spending more on defence, but this project does risk eating the rest of the defence capability plan alive – potentially impacting other critical areas of defence investment.

The risks are high, but the rewards are even higher. The world we are living in has changed. Great power competition in our region is rising. Australian sovereignty is under more risk than at any time since the 1940s. Security, the prime minster has declared numerous times, is his number-one priority.

In the new era of strategic competition, investments such as AUKUS are investments in our long-term security and sovereignty and hedge against an unknown and high-risk future. The risks and costs will be high, but peace and prosperity always come at a cost. AUKUS is a whole-of-nation endeavour.

While the costs are unknown and the risks high, the potential payoff is significant and the strategic rationale is clear.