In a curious way, this fear of attacks on national territory recently played out in China’s state-run Global Times. According to the communist party media outlet, the possibility of Australia buying the B-21 bomber “would enable Australia to launch long-range strikes against China, thus posing serious threats to China”. In contrast, Australia buying nuclear submarines appears a matter of nuclear proliferation, not some clear danger to China. Such a difference in understanding suggests B-21s might deter, while SSNs maybe not as much.
AUKUS now gives Australia a whole new submarine deterrence option to consider. The agreement allows Australia considerable nuclear leeway with the United States and United Kingdom. Britain is building four Dreadnought Class ballistic nuclear missile submarines (SSBNs). These will be armed with 12 US-made Trident intercontinental missiles, each with eight individually targetable nuclear warheads. Starting in the early 2030s, patrolling Dreadnoughts will hold at risk any Russian or East Asian target.
Australia could join with the United Kingdom in acquiring, manning, operating and sustaining the small Dreadnought fleet. This means both nations would need to mutually agree to use the missiles. There are few nations that could make such a nuclear-sharing deal work, but Australia and the United Kingdom potentially could.
Australia would not get nuclear weapons under such a deal or even nuclear-powered submarines for its sole use. Indeed, such a shared SSBN idea would not be wholly new. For many years, the US has shared nuclear weapons with Belgium, Germany, the Netherlands, Italy and Turkey; proliferation concerns have already been addressed.
Australia would outwardly seem to have access to a long-range, highly survivable nuclear strike option for situations of dire national danger. This would significantly deter any great powers starting a war with Australia, something simply having SSNs will not do.
Australia’s new SSN force planned for the 2040s and beyond will be great ship killers. They will effectively be today’s Collins submarines on steroids, but no more. An alternative that might stop a war from ever starting seems worth considering. A sharing option would also be faster to enter service and probably rather lower cost. An expensive SSN plan won’t decisively influence the minds of potential aggressors. However, an SSBN-sharing arrangement under AUKUS definitely would.