On one hand, Australia strongly opposes acquiring nuclear weapons and backs non-proliferation. On the other hand, it increasingly depends on the US for extended nuclear deterrence.

The contradiction is implicit in the AUKUS program, just below the surface. Yet AUKUS, a strategic partnership with two trusted nuclear-armed powers, also offers an ideal framework for developing Australian thought and practice on nuclear deterrence.

AUKUS has been branded and communicated as a conventional capability-development initiative, emphatically not about nuclear weapons. But it’s fanciful to assume that AUKUS will deliver nuclear-powered attack submarines, hypersonics and other advanced military capabilities while remaining firewalled from nuclear strategy.

Non-proliferation has been a theme in Australia’s foreign policy for decades. Since AUKUS was first announced in 2021, Liberal-National and Labor federal governments have reaffirmed Australia’s intention not to acquire nuclear weapons. Defence officials and diplomats have been at pains to reassure domestic critics and the region that handling nuclear fuel for Australia’s future submarines under AUKUS will pose no proliferation risk. Indeed, they have presented AUKUS as a best-practice opportunity in nuclear stewardship, underscoring Australia’s non-proliferation credentials. On 31 May, in Singapore, the minister for defence, Richard Marles, expounded upon non-proliferation themes in his speech at the Shangri-La Dialogue, once again highlighting AUKUS as an example of ‘the highest safeguard standards’.

Australia’s basic aim for AUKUS is to develop advanced military capabilities, including ‘conventionally armed, nuclear powered’ submarines. AUKUS is often associated with deterrence. But from the start the initiative has been insulated from discussion of nuclear deterrence, presumably in order to avoid sending mixed signals about Australia’s strategic intentions.

That’s not because there’s a risk that Australia will covertly divert submarine fuel for weapons production. The possibility is minuscule. But Canberra’s needle-like diplomatic focus on ensuring AUKUS complies with non-proliferation standards distracts from a more basic dilemma confronting Australia’s military strategy: how can a country without nuclear weapons of its own deter nuclear-armed states such as China, North Korea and Russia from military adventurism? In particular, how can it do so when they are building up their nuclear arsenals, blurring the line between nuclear and conventional capabilities and likely to issue nuclear threats designed to deter the US and its allies from armed intervention?

Canberra’s all-weather solution to this knotty dilemma is dependence on the US nuclear umbrella. But the credibility of Washington’s extended nuclear guarantees has steadily eroded, in part because successive administrations have failed to keep pace with increasing complex nuclear threats in the Indo-Pacific and to quickly acquire a greater variety of nuclear and other weapons that would give the US more strike options.

For Australia’s defence strategy to be viable against nuclear powers, conventional deterrence needs to be conceptually married to the nuclear domain. Canberra’s fidelity to non-proliferation norms should not distract from this sensitive but pressing requirement. In reality, AUKUS exists in a strategic context where both adversaries’ and allies’ nuclear arsenals are already factored into planning for high-intensity conflict. As China builds out its nuclear forces to support a strategy for regional war, thresholds for nuclear use will become increasingly blurred.

The US proposes to arm attack submarines with submarine-launched nuclear-armed cruise missiles, SLCM-Ns. The current US Indo-Pacom commander wants this ‘at the soonest possibility’. This means Australia’s Virginia-class submarines will probably be operating alongside nuclear-armed US counterparts next decade. To maintain credible, full-spectrum military deterrence, and avoid a choice between suicide or surrender during a major conflict with China, the US will probably operate more nuclear-armed vessels and aircraft from Australian bases, with the full knowledge and concurrence of the Australian government.

To deter nuclear-armed adversaries, or fight them if deterrence fails, Australia’s conventional military capabilities, including those developed via AUKUS, will need to be closely integrated with US forces, including its nuclear-capable assets. As alarming as this may sound to Australians, it is less disturbing than the alternative of resorting to an independent nuclear deterrent.

So much for the problems. But AUKUS can also be part of the solution to straddling Australia’s divided strategic personality.

It provides a ready-made framework for Australia to develop its thinking and options for full-spectrum deterrence against nuclear-armed adversaries, including China. This doesn’t mean Australia will acquire nuclear weapons through AUKUS. Instead, AUKUS can help Australia to develop its deterrence requirements across the spectrum of conventional and nuclear threats and identify new ways to support extended nuclear deterrence.

It makes sense for Washington to engage Canberra more on extended nuclear deterrence, as it already does with Japan and South Korea, given Australia’s expanding host footprint for US strike assets. Adding Britain’s complementary perspective as a nuclear weapons state would help, much as the British role provides ballast elsewhere within AUKUS. Britain’s nuclear forces are stretched and focused on the Euro-Atlantic, so coverage is unlikely to be extended to Australia. But Britain will still have to factor China’s expanding nuclear arsenal into its own deterrence calculations and future nuclear force posture. So there’s value for Whitehall, too, in exploring the nuclear deterrence dimensions to the AUKUS partnership.

Given the controversy that nuclear weapons generate, adding another focus area to AUKUS’s crowded agenda may be a difficult sell. But pretending that AUKUS has no relationship to nuclear weapons isn’t doing Australia any favours. Some nuclear matters will be more appropriately raised bilaterally via high-level ministerial meetings with the US and Britain (and perhaps they already are). But for AUKUS’s long-term strategic coherence, the three partners should start consulting trilaterally on nuclear deterrence, without prejudice to Australia’s non-proliferation credentials.

Using the AUKUS framework for this purpose would be more profitable for Canberra than following a regional collective approach, in which Australia would be competing for US attention with Japan and South Korea, who have more immediate nuclear assurance needs.