The challenge of creating and breaking coded messages has been a crucial part of intelligence work for centuries. From cracking cyphers to intercepting communication networks, the incidentals of signals intelligence (Sigint) have adapted over time, but the fundamentals have stayed the same: to define the intent of adversaries.

In Revealing Secrets, John Blaxland and Clare Birgin explore the (unofficial) history of Australian Sigint and its role in the cyber domain. In scope, the book covers an array of topics through ten chapters, including the evolution of Sigint in Australia, the royal commissions and reviews that shaped its legal and ethical framework, the challenges and opportunities posed by the emergence of cyber, and the significance of Australia’s alliance with its key intelligence partners. In doing so, Blaxland and Birgin offer a perspective on how Sigint has shaped and been shaped by Australia’s national security interests.

But it is the art of cryptography that forms the theme of the first chapter. The authors trace the subject and its background by looking at the evolution of technology and its impact on the interception and decipherment of signals in the ancient world. From classical times to the modern era, the potted history of how Sigint has been used as a form of statecraft, largely driven by technological innovations in the late nineteenth century, transformed Sigint into a sophisticated system of information gathering. They show how the British Empire pioneered the development of radio and wireless interception and how Australia followed its lead, albeit in a subordinate role.

The value of Sigint in the Boer War and the First World War is demonstrated by examples of maritime and land operations that increasingly relied on it. The main contribution of these chapters to the history of Australian intelligence is that they fill a gap in early Sigint history that has been largely undocumented by other scholars. However, there are some limitations in terms of the book’s descriptions. There is a tendency to focus more on the British and American experiences, with only occasional references to Australia. But the authors make the implication clear: Australia did not have its own Sigint capabilities at this time, and instead depended on those of its imperial allies.

When the Second World War engulfed the Pacific, Australia’s own resources for intercepting and deciphering enemy communications were meagre. The heroic efforts of a few visionary men, such as Eric Nave of the Royal Navy, who pioneered the art of breaking Japanese codes and established the Special Intelligence Bureau in 1940, are given a sound treatment. The exploits of Sigint during the great conflict are recounted in detail, especially those decisive encounters at the Coral Sea and Midway.

It is at this time that Australia began to forge some crucial bonds of friendship and cooperation with other nations. Some discussion is devoted to the Holden and BRUSA (later UKUSA) Agreements, which laid the foundations for the Five Eyes alliance, but analysis again gives way to chronology. These agreements are of historical significance and had far-reaching consequences for Australia’s role and influence in the world of intelligence. But their full implications are not explored or explained in this section. It was from these agreements that a new order of Sigint would emerge — an order that would shape and define Australian security policies into the twenty first century. One of the most celebrated examples of this collaboration is the Venona program — a US Army Signals operation intercepting Soviet diplomatic cables emanating from its embassies (including Canberra) — which is invoked with reverence. But there is a distinct absence of any fresh insights or revelations, beyond the prevailing literature, regarding the involvement of Australian Sigint in this program, which will leave the reader unsatisfied.

Latter sections of the book deal with the aftermath of the war and the reorganization of the Australian signals departments. The authors give a ponderous account of the changes in structure and strategy that occurred during this period and devote considerable attention to the Korean and Vietnam Wars. What these chapters show is how Australia’s involvement in these conflicts strengthened its ties with the US intelligence community, leading to the notorious Five Eyes agreement. These developments are outlined in detail, but lack any critical treatment of key points. For instance, the implications of establishing joint intelligence facilities and operations such as Pine Gap, Nurrugbar, and North West Cape, especially during the Cold War, are largely muted. These facilities have been the focal points of public scrutiny and debate for decades, and have also served as the glue that holds together the intelligence partnership between the two nations. There are some insights into the political dynamics that shaped the establishment and operation of these facilities under different governments, but they do not explore in depth the implications of such arrangements for Australia’s security. How, or indeed, whether these facilities have exposed Australia to greater risks from potential adversaries is a question that remains largely unconsidered.

One point of emphasis in the latter half of the book is how the development of technology throughout the twentieth century was accompanied by a corresponding expansion of signals capabilities. As technology advanced so too did to the ability to collect information and use it as a means of surveillance or espionage.

The book offers some thoughtful insights into the impact of satellite communications and space-based interceptions as well as the advent of the electronic age in the last decades of the twentieth century. This brought with it a new set of challenges and opportunities for the Australian intelligence community. The old methods of intercepting and deciphering radio signals were no longer sufficient to cope with the vast and complex network of digital communications that spanned the globe. The emergence of mobile devices, the internet, and the threat of cyber-attacks required a radical transformation of Australian Sigint capabilities. New entities were born: the Australian Signals Directorate and The Cyber Security Centre, tasked with defending the nation’s cyberspace and conducting offensive operations against its adversaries.

The book’s value lies in its capacity to synthesise more of the disparate elements that constitute the totality of Australian intelligence history, and this story will keep the reader interested. However, the book is confined to a chronological account of events without much analysis or interpretation. Those expecting any new critique of the key events will be left wanting. Having said this, Blaxland and Birgin’s history of Australian Sigint does enrich the existing literature on the topic and contributes to the epistemic foundation. Revealing Secrets is a welcome account of a hidden but important aspect of Australian statecraft that will appeal to most interested in intelligence history and international relations.

This is a review of John Blaxland and Clare Birgin, Revealing Secrets, An Unofficial History of Australian Signals Intelligence and the Advent of Cyber (UNSW Press, 2023) ISBN 9781742237947.

Justin T. McPhee is a Melbourne researcher and academic. He is the author of Spinning the Secrets of State: Politics and Intelligence in Australia.

This review article is published under a Creative Commons License and may be republished with attribution.