Australia's 'Optimal Pathway' to acquiring and maintaining a nuclear-propelled, conventionally armed submarine capability from the 2030s and beyond has been agreed by all three AUKUS nations and is a matter of public record.1 This paper is supportive of pursuing that path. To be clear: AUKUS represents the best opportunity for Australia to acquire an essential strategic capability underpinning its future defence. However, the Optimal Pathway has significant cumulative risk involved. There are three major complex enterprises that must all align if Australia is not to experience a serious gap in its sovereign submarine capability in following this path. Those are the Collins-class life-of-type extension (LOTE), the transfer of three or more Virginia-class nuclear attack submarines (SSNs) from the US, and Australia's construction—with UK and US assistance—of the SSN-AUKUS, which is to be a new class of SSN submarines for the Royal Australian Navy (RAN).
Australia's defence plans require a sovereign submarine capability to be effective. 'Sovereign' in this sense means under Australia's national control. The potential capability gap that we're describing as a risk is—in terms of submarine acquisition—an awkward one. It could emerge suddenly. It's probably too long a period for Australia to run the risk of being without an essential capability, but it isn't a long time to acquire and operate a new class of submarine.
To assist in managing these three areas of separate but compounding significant risk, Australia should explore the backup option of leasing or otherwise rapidly acquiring small numbers of an advanced conventional submarine capability from Japan. Japan has a comparatively large, 'young', highly capable conventional submarine fleet. It has two active production lines that together turn out an advanced submarine each year and have the potential to ramp up production even further. It's also one of Australia's few international partners with the depth of trust and a similar view of the international security situation necessary to make this option a viable one.
Given the depth of the request that Australia would be making of Japan, engagement needs to begin now for this option to be a realistic possibility.
The only type of submarine that can meet all of Australia's requirements is an SSN; but, in its absence and to bridge any gap that emerges as best we can until one becomes available, it's necessary to investigate alternatives to cover a major known contingency. A capable sovereign submarine capability is a core requirement for Australia's defence over the next two decades, and there are known risks that could prevent that happening. Exploring a relatively modest alternative such as leasing from Japan seems prudent—and it needs to begin now if it's to be useful in time.
1Australian Submarine Agency (ASA), 'AUKUS', Australian Government, no date, online .
