Last year, as part of the broader discussion about a Plan B for Australia’s defence strategy, I started a series ^[1] looking at Australia’s options to project military power in an age in which we could no longer take American military primacy for granted. The series considered long-range strike options built around bombers and variants of the F-35. In coming weeks, I’ll look at other options, such as long-range missiles, submarines and cyber warfare.

My consideration doesn’t include nuclear weapons. I’m hesitant to say it’s limited to ‘conventional’ options because some potential approaches could in fact be quite unconventional, like cyber. But I’ll use the term conventional to mean non-nuclear. The other point to emphasise is that the Plan B discussion ^[2] is set in the context of changing power relativities between the US and China. But it’s not judging the US’s willingness to defend Australia; it’s simply acknowledging that it will likely have less capacity to do so and it’s important for us to look at what we can do to help ourselves within the alliance.

My pieces are part of a larger discussion about the purpose and viability of long-range strike options for Australia (here ^[3] and here ^[4], for example). But there are very different views on what we need a strike capability to do and—just as importantly—what we can’t expect it to do. At the nub of the argument is the question of whether Australia could ever have a large or potent enough conventional strike capability to influence the behaviour of a hostile great power.

To paraphrase the sceptics, having a strike capability is pointless, and in fact self-destructive, because any conventional strike on a major-power adversary’s homeland would inflict minimal damage and be repaid 10 times over. It’s a fair point, and one that I considered so obvious I hadn’t discussed it. I’m not saying we should get a long-range strike capability to bomb a major-power adversary’s homeland.

But then what do we want it for? Let’s take a step back and have the framing discussion I skipped over at the start of this series. It useful to begin with deterrence theory (noting that much of its history and application arises from the nuclear context). Here’s a useful primer ^[5] by the RAND Corporation’s Michael J. Mazarr on deterrence for people who are too busy to do a degree in strategic studies.

The two primary forms of deterrence are deterrence by denial and deterrence by punishment. The former seeks to deter by increasing the difficulty of the adversary’s achieving their goals to the point that they regard the risk and investment of resources necessary to not be worth the cost. The latter seeks to deter by imposing penalties. Those penalties could be nuclear, but they could take other forms, such as economic reprisals.

Mazarr argues that the most important thing is that deterrence ‘must be conceived primarily as an effort to shape the thinking of a potential aggressor’. That is, the effectiveness of deterrence depends on its ability to shape the perceptions of the potential adversary, and therefore is specific to their ‘interest, motives, and imperatives’. It’s very context-specific.

This leads to a second key point. Deterrence by denial is more direct—if you seek to attack my territory, I’ll put more troops and weapons there. Deterrence by punishment involves a more indirect response so it can be harder to understand how you are, or aren’t, shaping an adversary’s calculus. For this reason, Mazarr notes, ‘most classic studies suggest that denial strategies are inherently more reliable than punishment strategies’ (although other theorists may disagree). A potential adversary can see that I am taking direct steps to bolster the defence of my territory. But they may not be convinced that I am going to launch a nuclear strike on their homeland if it could prompt a retaliatory nuclear strike on mine.

Because deterrence is about shaping potential adversaries’ perceptions, what works against one may not work against another because the latter may be willing to pay a higher price. Similarly, what works against one may not always work because its willingness to pay a price may change as its own threat perceptions change. And crucially, deterring an adversary from one course of action can lead them to take another one which presents other threats and therefore requires other responses.

In my next post, I’ll look at what all this means for an Australian long-range strike capability.