Elevated to a military science during the Cold War, deterrence is a relatively new task for the Australian Defence Force.
Traditionally, Australia’s armed forces have lacked the mass, range, lethality and ability to project force to deter a significant military power, except as part of coalition operations. But the Defence Strategic Review of 2023 recommended tasking the ADF with a deterrent role.
Thomas Schelling, a leading thinker on deterrence, defined it in Arms and Influence as being ‘about intentions—not just estimating enemy intentions but influencing them’, which he called the hardest part. The signalling of a credible ‘if x, then y’ statement, in the hope that threatening x ensures y action never has to be taken, is the essence of deterrence. Washington’s deployment of two aircraft carrier strike groups to the Eastern Mediterranean in late 2023 was a textbook deterrent message to any external actor contemplating intervening in the Israel–Hamas war: ‘Don’t, or else.’
As history warns, deterrent messages must always be backed by credible threats. Australia should refrain from issuing hollow threats it does not have the stomach and capacity to act on, lest it shatter the credibility of its future threats and sound as British prime minister Neville Chamberlain did on 31 March 1939 when, haunted by the ghosts of Czechoslovakia and Austria, he made what Hitler interpreted as a panicked and unenforceable vow to defend Poland. Far from deterring the dictator, Chamberlain’s words were ’the precipitating cause’ of his invasion. Nazi Germany was immune to British and French deterrence signals not because Germany was undeterrable but because Hitler accurately dismissed the threat of an allied offensive across the Siegfried Line as a bluff.
Just as a non-credible threat only advertises its own bankruptcy, so a poorly communicated threat can invite dangerous misperception, even if it is backed by real capability and intent. The history of the 5th century BC Peloponnesian War by Thucydides offers a classic example of how a failure of deterrence unleashed one of the most cataclysmic wars of antiquity. At the height of the crisis, a vaguely worded Spartan ultimatum fatally underplayed that continental juggernaut’s unshakeable will to go to war. The Spartan king Archidamus II’s credible threat was tragically garbled, causing the Athenian leader Pericles to underestimate his adversary’s resolve. A hubristic pro-war speech by Pericles framed the Spartans as too weak to fight a naval war, one the Spartans won by destroying the Athenian fleet.
The lessons for Australia’s own deterrence efforts are enduring. Chief among them is that to credibly deter adversaries, Australia must impress on them both its capability and intent to ‘act to meet the common danger’, as the ANZUS Treaty succinctly puts it. And what that means, as uncomfortable as it may seem, is that Australia must be willing to threaten and win the war it earnestly hopes to prevent. AUKUS gives Australia the capability to make the targets of its deterrence campaign take the signals seriously, while it is the task of a broader Australian statecraft effort to ensure that its deterrent message—the ‘or else’—is believed.
Since Australia lacks the United States’ formidable military capabilities and the capacity to project them across oceans, Canberra’s deterrent language will lack much of the range and resonance of Cold War-era practice. This means that the red lines Australia draws and guards with deterrent threats will have to be defined exceedingly cautiously. Building an independent Australian deterrent—a sovereign line of effort separate from its crucial joint deterrence measures with the United States—will demand that Canberra be more clear-headed and disciplined than it has ever been in prioritising our nation’s military strategy.
Given the long timescale of the AUKUS project, an Australian doctrine of deterrence cannot assume a fixed, inter-generational threat as US planners could from the time of George Kennan’s Long Telegram in 1946 to the crumbling of the Berlin Wall. Leaders come and go. Economies boom and bust. Governments rise and fall. Strategic tensions wax and wane. By the time Australia operates its full fleet of nuclear-powered submarines, their first war-time deployment may be in circumstances completely unthinkable today.
That is why critics of AUKUS take the bait of foreign propagandists when they assume that it targets one specific country—call it ‘Musoria’, as I did alongside generations of Australian soldiers fighting that fictitious enemy out bush—in answer to one contingency. It simply does not. Nuclear-powered submarines are a country-agnostic capability that can respond along a broad spectrum of contingencies ranging from great-power war to insidious grey-zone threats. Australia has no fixed enemies, only permanent interests. While military planning must be granular and enemy-specific, the overarching strategy of deterrence needs the flexibility to adapt to multiple shooters.