91É«ÇéƬ

AUKUS is usually described as a defence technology partnership. Nuclear-powered submarines dominate public discussion, accompanied by promises of advanced artificial intelligence, quantum technologies, undersea capabilities and increasingly integrated defence industries.

Yet the success of AUKUS may depend upon a less visible form of interoperability.

Australia, the United Kingdom and the United States must ensure not only that their weapons, communications systems and armed forces can operate together, .

Military interoperability is generally understood in practical terms, but currently these expectations lean more towards the theoretical than the realistic.

Allied forces should be able to communicate securely, share intelligence, exchange information and operate compatible equipment. An Australian submarine should be capable of working alongside American and British vessels. Military headquarters should be able to plan operations jointly. Personnel should be able to move between allied commands without encountering unnecessary technical or procedural barriers.

These capabilities are essential. They are also only part of the problem. Australia, the United Kingdom and the United States possess closely related legal traditions, but they do not make decisions about war in the same way. Each country distributes authority between the executive, legislature and military through different constitutional arrangements.

Each of the three allies has developed different practices governing the deployment of armed forces, parliamentary scrutiny, military command and accountability for decisions made during conflict. They are nowhere close to dovetailing together in a way that would allow quick, decisive and commonly agreed decisions in times of war.

These differences become more important as military integration deepens. An Australian officer may serve within an American-led headquarters. Australian personnel may operate British-designed technologies while relying upon intelligence collected by the United States. Australian submarines may participate in operations planned through multinational command structures and supported by allied logistics, communications and targeting systems. The military components may operate seamlessly but legal authority does not necessarily travel with them.

Australian participation in a wartime operation must remain authorised under Australian law. The fact that an allied government has approved an operation does not itself provide authority for Australian forces to participate. Nor does the existence of an integrated command structure remove the responsibilities held by Australian ministers and military commanders.

This is not a theoretical concern. Modern military operations increasingly depend upon networks rather than nationally isolated forces. Intelligence may be collected by one country, analysed by another and used by a third. A targeting recommendation may pass through several national systems before reaching the person responsible for approving an attack. Autonomous and artificial intelligence-enabled technologies may make these relationships even more complex.

The closer these systems become, the more difficult it may be to identify where one country’s decision ends and another’s begins. AUKUS therefore raises questions extending well beyond the acquisition of submarines.

Who authorises the use of shared capabilities? Which country is responsible when information supplied through an allied system contributes to an unlawful outcome? How should Australian commanders respond when an allied direction is inconsistent with Australian legal obligations or government policy?

Interoperability cannot mean that constitutional differences disappear beneath technological integration.

Australia’s constitutional arrangements are distinct from those of its AUKUS partners. Our legal authority for operations are different. How .

The executive (the leaders of the Government of the day) possesses broad authority over defence and military operations, while the broader Parliament controls legislation, expenditure and political accountability.

The command of the Australian Defence Force is also governed by Australian statute. Australian personnel remain subject to Australian military law regardless of the nationality of the commander under whom they may temporarily serve.

These arrangements cannot simply be replaced by alliance practice (in a way that, say, coalition forces worked when operating in Iraq 2003). These are constitutional matters, above the idea of how different legal obligations are interpreted.

The challenge is particularly significant because military integration may gradually shape political decision-making. When personnel, technologies, supply chains and operational planning are deeply connected, governments may find that strategic choices have already been narrowed before a formal decision is made.

There is a further risk - interoperability can create capability, but also create dependency. If Australia becomes reliant upon allied intelligence, technology and logistical support, declining participation in a future operation may become practically difficult even where it remains legally possible. Decisions about military integration made years earlier may influence the options available to future governments.

That does not make AUKUS undesirable. Alliances necessarily involve cooperation, trust and some degree of mutual reliance. The purpose of interoperability is to allow countries to respond together when their interests and obligations align.

But integration should not be mistaken for automaticity. Australia must retain the ability to make independent decisions about the use of its armed forces. Its military commanders must remain accountable through Australian institutions. Its legal obligations must continue to apply even when Australian personnel operate within allied systems.

Parliament also has an important role. AUKUS will involve public expenditure and strategic commitments extending across generations. Parliamentary scrutiny should therefore examine not only the cost and delivery of military technologies, but the constitutional consequences of deeper integration.

The central question is not whether Australia should cooperate closely with its allies. It is how that cooperation can remain consistent with independent political judgment, lawful military command and democratic accountability.

Shared weapons may allow allies to fight together. Shared legal understanding will determine whether they can do so lawfully, responsibly and with public legitimacy.

Ìý