There is a comforting fiction at the heart of much contemporary strategic thinking: conventional military capabilities can substitute for nuclear deterrence without requiring the same political will. It is a neat idea—reassuring, technologically optimistic, and politically convenient. It is also dangerously wrong.

Deterrence does not reside in platforms, precision, or posture. It resides in belief—specifically, the adversary’s belief that you are both capable of inflicting costs and willing to do so. Strip away that second element, and deterrence collapses into theater.

This is the central problem confronting Australia and its allies as they navigate a rapidly shifting Indo-Pacific security environment. As nuclear risks grow, particularly with China’s expanding arsenal, there has been a noticeable intellectual pivot toward elevating conventional capabilities as a more “usable,” credible, and politically palatable form of deterrence. Long-range strike, autonomous systems, undersea warfare, and advanced ISR are all presented as tools that can impose meaningful costs without crossing the nuclear threshold.

However, this argument only holds if those tools are used. Too often, the debate stops at capability acquisition. Billions are spent, platforms are announced, doctrines are drafted. Yet, there is a conspicuous silence when it comes to the harder question: under what circumstances would Australia employ these capabilities in anger? What thresholds trigger their use? What risks are we prepared to accept in doing so?

Without clear answers, the signal sent to adversaries is not strength, but hesitation. Consider the logic from the perspective of a competitor. If Australia invests heavily in long-range strike but avoids articulating when it would employ it, an adversary may conclude that those capabilities are politically constrained. If grey-zone coercion, such as the deployment of sea mines, harassment of maritime assets, or interference with undersea infrastructure, does not elicit a forceful response, then the lesson learned is not deterrence, but permissiveness.

In this sense, ambiguity is not always stabilizing. It can just as easily invite probing. The uncomfortable reality is that conventional deterrence demands a level of resolve that many policymakers are reluctant to acknowledge. Unlike nuclear weapons, whose very horror lends them a paradoxical clarity, conventional forces sit in a murkier space. They are more usable, but precisely for that reason, credibility hinges on demonstrated willingness.

A missile that will is restricted from use is not a deterrent. A submarine that will not be deployed into contested waters does not shape adversary behavior. A cyber capability that remains permanently in reserve does not impose costs. Deterrence, in the conventional domain, is performative. It must be signaled, exercised, and at times demonstrated.

This does not mean recklessness or a rush to escalation. It means recognizing that deterrence is not cost-free. If the objective is to prevent adversary action, then one must be prepared to act before the situation becomes intolerable. Waiting until costs are imposed on you, economically, militarily, or politically undermines the very logic of deterrence. This is where much of the current discourse falls short. There is a tendency to treat conventional capabilities as inherently stabilizing, as though their mere existence alters adversary calculations. But capabilities without credible intent are inert. Worse, they can create a false sense of security, masking the erosion of deterrence beneath a veneer of preparedness.

The challenge is particularly acute for middle powers like Australia, which rely heavily on alliances and extended deterrence. As questions grow around the credibility of U.S. nuclear guarantees, especially in a more contested and multipolar environment, there is an understandable desire to bolster national self-reliance through conventional means. This is a sensible objective. But it cannot be achieved through hardware alone.

If conventional forces are to serve as a substitute or even a supplement to nuclear deterrence, then they must be embedded within a clear framework of political resolve. This requires more than capability development. It requires declaratory policy, strategic signaling, and a willingness to accept escalation risks.

For example, if the laying of sea mines in Australian waters is deemed unacceptable, then that must be stated clearly and backed by a credible commitment to respond with force if necessary. Anything less invites incremental encroachment. Over time, such encroachment normalizes behaviors that would once have been considered intolerable.

History offers ample evidence of this dynamic. Deterrence erodes not in dramatic moments, but through a series of small, unchallenged actions that cumulatively shift the baseline of what is acceptable. By the time a clear red line is crossed, it is often too late as the adversary has already recalibrated expectations.

The solution is not to abandon conventional deterrence, but to take it seriously. This means confronting uncomfortable questions. Are we prepared to use long-range strike capabilities against an adversary’s military assets in the initial stages of a crisis? Would we target grey-zone actors operating below the threshold of armed conflict? How do we signal our intentions without triggering the very escalation we seek to avoid? There are no easy answers, but avoiding the questions altogether is not a strategy, it is an abdication.

Ultimately, deterrence is about shaping perceptions. It is about convincing an adversary that the costs of action will outweigh the benefits. This cannot be achieved through ambiguity alone, nor through capability acquisition in isolation. It requires a coherent integration of means, messaging, and above all else, will.

If policymakers are unwilling to countenance the use of conventional force, then they should be honest about the implications. In such a scenario, conventional capabilities do not replace nuclear deterrence; they merely decorate its absence.

The risk is not just strategic failure, but strategic surprise. An adversary that perceives a gap between capability and intent will exploit it; once that perception is formed, it is exceedingly difficult to reverse.

Deterrence, in the end, is a test of credibility and resolve. It is not measured by what you possess, but by what an adversary believes you will do. In strategic competition, credibility is not claimed; it is proven and without resolve, deterrence is nothing at all.

Natalie Treloar is the Australian Company Director of Alpha-India Consultancy, a Senior Fellow at the Indo-Pacific Studies Center (IPSC), a Senior Analyst at the National Institute for Deterrence Studies (NIDS), and a member of the Open Nuclear Network. Views expressed in this article are the author’s own.

Deterrence Without Resolve Is No Deterrence at All was originally published on Global Security Review.

The reality is that Americans live in an increasingly complex threat environment, and the credibility of the nuclear deterrent ultimately depends on America’s ability to respond to technical or strategic surprise. That includes being ready, if necessary, to conduct a nuclear test.

There are multiple and specific conditions under which the US might be compelled to resume underground nuclear testing, each involving serious strategic or technical concerns that cannot be resolved through non-explosive means as directed by the Stockpile Stewardship Program obligations.

From an American strategic perspective, it is possible that a future administration or Congress could determine that the long-standing moratorium on nuclear testing no longer serves American interests. For example, if credible intelligence revealed that an adversary, such as China or Russia, were conducting yield-producing tests, particularly to develop new capabilities or gain strategic advantage, then confidence in the existing deterrence balance could be undermined.

Adversary behavior is a factor the United States cannot ignore. China and Russia maintain active test sites and appear to be positioned to resume testing on short notice. If either nation were to conduct a low-yield test that altered the strategic balance, the US would need to respond—not necessarily by testing, but by demonstrating that it is able. Detecting and interpreting data from these tests may result in the restoration of confidence in the status quo.

Should a nuclear-armed adversary employ or threaten limited nuclear use, a carefully calibrated test could be used to demonstrate resolve, reassure allies, stabilize the situation, and deter further escalation. Such signaling would carry substantial diplomatic consequences and would only be contemplated under extraordinary circumstances.

In addition to strategic drivers that might lead to the resumption of nuclear testing, various technical issues might force America’s hand. For instance, the inability to certify the stockpile through the Stockpile Stewardship Program, such as technical issues with weapons or their components, might also be a driver to resume full-scale nuclear testing.

One such condition would be the emergence of significant doubt about the reliability or safety of an existing warhead type. As the stockpile ages, performance uncertainties can develop in critical components such as plutonium pits, high explosives, or firing systems. If these concerns cannot be resolved through laboratory experiments, modeling, or subcritical testing, a nuclear test might be required to validate performance or ensure safety margins. Such a step would follow a determination by the Nuclear Weapons Council and the national laboratories that non-testing alternatives are insufficient.

A second issue involves the development and certification of new warhead designs. While current policy emphasizes life-extension programs using legacy designs, future geopolitical or technological developments could prompt the US to pursue novel nuclear systems. For example, if the Department of Defense sought a warhead optimized for hypersonic delivery or deeply buried targets, such a design might require full-scale testing for certification—particularly if it deviates from previously tested architectures.

Lastly, there is also the possibility of future weapon development. While current policy focuses on life-extension programs, emerging mission needs may eventually require new designs. If those designs fall outside the range of previously tested systems, the US may have no choice but to test them to certify performance.

Should the United States confront a situation where confidence in warhead reliability or safety can no longer be assured through non-explosive means, or where geopolitical developments erode the credibility of deterrence, a timely and technically sound return to testing may become necessary. However, should the US resume testing for any reason, a great number of challenges will need to be met and overcome.

During the four decades of active nuclear explosive testing, the US developed a strong and thorough testing infrastructure and mindset. As nuclear explosive weapon technology evolved, so did the methods of executing tests and measuring the performance of devices. Facilities, mostly in Nevada, were built and staffed to provide an environment capable of supporting test activities and all the personnel required to perform the tests.

These tests required the expertise of scientists from multiple disciplines, engineers of various specialties, program managers, environmental control technicians, and a wide array of support staff. In addition to the technical workforce, entire teams were responsible for sustaining day-to-day life at remote test sites—providing essential services such as food, water, housing, sanitation, medical support, and logistics.

A rough estimate of the numbers of personnel required to execute an active testing program can be found in a 1981 Department of Energy Nevada Operations Office Newsletter. There were 240 federal employees, 7,100 contractors (laboratory and university personnel), and 11,300 southern Nevada support jobs. Unfortunately, just bringing together the wide variety of personnel needed to execute and support testing is only meeting an obvious challenge. A more subtle challenge is relearning how to keep any explosive test from eaking out of the ground and into the atmosphere.

A resumption of testing would still require the US to meet the obligations of two in-force international treaties; the Threshold Test Ban Treaty (TTBT), which limits the explosive yield of any test to 150 kilotons (kt), and the Limited Test Ban Treaty (LTBT), which bans all above ground and underwater tests. Compliance with the 150 kt limit on explosive yield can be easily maintained because scientists from the national laboratories can confidently ensure the magnitude of the yield will not exceed the limit.

Compliance with the obligations of the Limited Test Ban Treaty presents a different challenge. The cadre of scientific, engineering, and technical experts who would conduct the test are unlikely to have ever faced the challenges of nuclear testing—ensuring the energy and radioactive debris is “contained” in the underground environment.

The cadre of experts who last tested a nuclear weapon, almost 35 years ago, had to “learn” how to meet this unique challenge. Most likely, none of the current cadre has ever been asked to deal with such a large amount of energy released in such a small time increment. Keeping a test contained underground is a vital national interest as a leak of radioactive materials from a nuclear test would cause significant harm to the nuclear enterprise.

Any resumption of nuclear explosive testing would represent a fundamental policy shift with far-reaching implications. A return to testing would affect arms control dynamics, global nonproliferation norms, and the strategic behavior of both allies and adversaries. For these reasons, the threshold for testing remains extraordinarily high, but it is not absolute. Given the challenges facing the United States, dramatic change may come when least expected. A requirement to test a nuclear weapon for strategic or technical reasons may be a part of that change.

James Ragland is a Fellow at the National Institute for Deterrence Studies. Joel Karasikis a contractor for the Defense Nuclear Weapons School.  The views expressed are their own.

It Is Time to Test Again was originally published on Global Security Review.