Suddenly and unexpectedly, a small but intense debate has ignited in Australia over an unlikely topic—the wisdom of acquiring an indigenous nuclear weapons arsenal. (Some of the contributions to that debate can be found here, here, here, here, here and here.) One of the more novel contributions was made in a recent post on the Lowy Institute’s blog, The Interpreter. The author, Peter Layton, suggested that Australia ought to consider the merits of ‘nuclear sharing’, either by deliberately strengthening its extended nuclear deterrence arrangements with the US or—more audaciously—by buying its way into a share of the British nuclear arsenal.

While his post examines both alternatives, it’s clear Peter favours ‘going British’. But at first glance there’d seem to be some serious hurdles in the way. For one thing, Australia still wouldn’t have full control over its own nuclear arsenal. Indeed, we’d be paying more—a lot more—to mimic an arrangement that the US already has with some of its key allies, but with a partner possessing a much smaller nuclear arsenal that’s typically deployed in the north Atlantic. Further, we wouldn’t be bringing anything to the table in terms of actual nuclear sharing; the Brits would be doing that, since it’s their arsenal. All we’d be sharing is money.

So I’d like to use this post to unpack two concepts of nuclear sharing: the kind we already enjoy as a US ally, and the kind we might be more interested in pursuing if we really were intending to proliferate.

Let’s start with the first. US allies around the world that benefit from US extended nuclear assurance participate in a range of supportive activities intended to strengthen the credibility of that assurance and to share the risks associated with nuclear deterrence. Some allies host US nuclear warheads. Some host the aircraft that would deliver those warheads. Some support nuclear operations by providing aerial refuelling or air defence for nuclear-armed aircraft. And some contribute less directly: Australia, for example, has long been a contributor to US strategic command and control, rather than to the weapons systems themselves.

This form of nuclear sharing makes the benefits of nuclear deterrence more widely available to US allies—and aims to forestall proliferation among a group of advanced Western countries that could, if they chose, cross the nuclear threshold with relative ease.

The second form of nuclear sharing—the form currently practised by North Korea and Iran—covers a set of activities intended to lift both parties over the nuclear threshold. Cooperation is typically built on the basis of a shared strategic agenda—as when China helped Pakistan with nuclear weapons design to frustrate India, for example.

This second form of sharing is anathema to many—because it smacks of proliferation rings, nuclear smuggling and illicit technology transfers. And, let’s be honest, sometimes the ‘sharing’ is involuntary; several nuclear weapons programs have depended on stolen information and technology. Still, as Jack Boureston and James Russell observe dryly, ‘None of today’s nine nuclear weapons states achieved their status without the assistance from people, information, equipment and/or sensitive technology that came from somewhere else.’ Thomas Reed and Danny Stillman, in their book The nuclear express, argue that all current nuclear programs have, over time, turned upon a shared pool of knowledge that can be traced back to the Manhattan Project—a research effort in which ‘less than a quarter of the senior technical staff at wartime Los Alamos, New Mexico, were native-born American citizens’.

In short, when the need to proliferate is strong, nuclear sharing (of this second kind) makes sense. Proliferating is hard work. Sharing the burden with others typically hastens the process by broadening both the human capital and the technological skill set upon which the potential proliferator can draw.

What might sharing arrangements involve? Well, in principle, they might occur across the full range of activities necessary to build, deploy and sustain a nuclear arsenal. There are opportunities for cooperation in acquiring fissile materials, designing and fabricating nuclear devices, testing nuclear weapons, constructing delivery vehicles, supporting each other’s nuclear operations, and so on. Parties to a sharing agreement might feasibly devise a cooperative venture at any point along that spectrum. They might cooperate on uranium enrichment, for example, but not on anything else. Similarly, they might cooperate on bomb design, or on nuclear testing, but not on delivery vehicles. Or they might cooperate only on delivery vehicles, steering clear of the more sensitive areas of cooperation.

Why is it worth thinking about this second form of nuclear sharing? For the simple reason that it might be about to enjoy a seminal revival. The first form of nuclear sharing is a core part of the global order forged by the US since the early days of the Cold War. While US alliances continue and extended nuclear deterrence endures, US allies have less incentive to proliferate. The second form gives us a picture of what a post-alliance world might look like.

In that world the Nuclear Non-Proliferation Treaty might not hold. For a number of states, a program of technical cooperation with a friend or partner would then offer the fastest route to successful proliferation. Some of those might see Australia, which has a record of close nuclear cooperation with both the UK and the US, as a potential partner for their own endeavours—despite the relatively underdeveloped nature of our nuclear sector.

Moreover, the shoe might well be on the other foot: in a darker Asian strategic environment, we might be the ones soliciting closer nuclear-sharing arrangements. If we were keen to proliferate quickly, where might we look for assistance?