The governance of outer space emerged in the crucible of the nuclear age. In 1963, the United States, the Soviet Union, and the United Kingdom signed the Partial Test Ban Treaty, prohibiting nuclear test explosions “in the atmosphere, in outer space and under water”. This landmark treaty was not only an environmental measure, but an important act of strategic restraint.
Four years later, the Outer Space Treaty entered into force, with Article IV prohibiting placing “in orbit around the Earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction.” This provision effectively institutionalized the idea that strategic stability in space was inseparable from nuclear restraint. The 1972 Treaty on the Limitation of Anti-Ballistic Missile Systems further reinforced that principle, restricting development, testing and deployment of missile defence, and space-based missile defence. This restriction recognized that space technology itself and the intent to pursue such technology could undermine stability if unconstrained.
These treaties acknowledged that introducing new avenues for nuclear competition into orbit could worsen crisis instability without delivering meaningful military advantage. As such, the early legal architecture of outer space was in large part about managing nuclear danger. For example, the Soviet Union in their remarks to a 1983 UNGA Special Committee debate warned that orbital systems designed to neutralize early-warning and command-and-control satellites could create conditions for a successful pre-emptive strike, while undermining confidence in the ability to retaliate. Thus, heightening nuclear escalation risks.
Yet, space activity has changed profoundly since the 1980s and so have some of the debates that couple it. Space-enabled services are more valuable to human wellbeing than ever before, and the space environment now includes thousands of commercial satellites and the continued advance toward cislunar and lunar exploration. Strategic anxieties persist amidst challenges of debris, congestion and sustainability; factors that do not always have a direct nuclear analogue. Re-examining the nuclear inheritance in a time of increased nuclear anxiety and proposed space-based missile defence is therefore useful. Not to overly emphasize it, but to rebalance it. Future protections need to be created to manage nuclear risk and escalation in outer space. These protections, however, should form the floor, not the ceiling, for a modern and inclusive approach to space governance.
The persistence of nuclear fragility
Modern nuclear command, control and communications (NC3) systems depend on satellites for early warning, detection and communication. This reliance introduces acute vulnerabilities since jamming, dazzling, cyber intrusion, or proximity operations can disrupt signals in ways that mimic or prefigure hostile intent. Experts have argued this phenomenon of entanglement between nuclear and non-nuclear systems creates pathways for inadvertent escalation, and space assets are certainly included. Recent research underscores how dual-use satellites and the influence of the private sector can confound strategic stability as differing incentive structures and ambiguous leadership roles make technical anomalies and activity difficult to interpret. Such activity may create even more escalation pathways, where misperception rather than intent could trigger a crisis.
The risk lies not only in technology but in psychology, as there is also a perception of vulnerability. Early warning satellites and space-based communications are anchors of deterrence. Any disruption, be it accidental or deliberate, can appear to threaten a State’s ability to detect or respond to a nuclear strike, creating powerful incentives for pre-emption. In this context, the Prevention of an Arms Race in Outer Space (PAROS) remains as relevant as ever. Though progress has often stalled, the idea of prevention—acting before destabilizing dynamics become entrenched—captures the essence of why shared restraint in space remains indispensable.
However, two key challenges complicate pursuing solutions to this problem.
- Asymmetry. Reliance on space assets differs markedly among nuclear-armed States, and the specific role and degree of reliance on space-based infrastructure within a State’s early-warning architecture remains unclear. As such, non-interference norms around NC3 satellites could disproportionately benefit the most space-dependent actors. Securing such commitments therefore requires a measure of empathy, or a willingness to safeguard a rival’s sense of security, even when the immediate advantage appears uneven. It is a difficult political ask, one that demands attempts at trust-building and mutual understanding before any formal measures can take shape.
- Inequality. Privileging nuclear systems risks re-entrenching a two-tier security order reminiscent of the broader asymmetries embedded in the nuclear non-proliferation regime. The logic that protects nuclear-armed States and their strategic assets can unintentionally reinforce hierarchies of vulnerability, leaving important civilian and humanitarian infrastructures comparatively unprotected. This framing could also narrow outer space security discourse to the threat perceptions of a few, treating space as an extension of nuclear deterrence rather than a shared environment with diverse users and collective risks. Ensuring stability in space therefore requires that the protections afforded to strategic systems be equally extended to the broader infrastructures that underpin human security and equitable access to the benefits of space.
The rise of space-centric challenges
While nuclear fragility persists, some of the most pressing space challenges today arise from the space environment’s own dynamics. The number of active satellites now exceeds 13,000 and constellations are projected to surpass 100,000 in the coming decade. This degree of densification escalates debris risks sharply, as well as further complicates spectrum allocation and harmful interference concerns. Exacerbating this problem, some national security debates are popularizing the concept of resiliency via redundancy to respond to space insecurity. This creates overlaps, constellation proliferation, crosslinking, and rapid launch replacement. In a global model where only one country pursued such a national security architecture, the environmental effects may be minimal. However, should multiple States adopt such a model, as is likely the case in the current multipolar context, the impact on the environment and international security relations would be damaging. Moreover, assessments on resiliency via redundancy have shown potential increased vulnerabilities to fragmentation events which may significantly increase the risk of consequential collision events. Large-scale redundancy architectures can also crowd orbital regimes and spectrum resources, constraining access for emerging spacefaring States and complicating efforts to uphold the Outer Space Treaty’s obligation to use outer space “on a basis of equality and in accordance with international law.”
Proposals for space-based missile interceptors often present large constellations as a route to deterrence by denial. Yet, technical modelling finds boost-phase, space-based architectures technically and economically challenging, requiring hundreds to thousands of on-orbit interceptors. These findings make space-based interceptor concepts as much a commons-management issue as a deterrence question. Any large in-orbit interceptor layer would add significant density to already congested orbits, with debris-hazard externalities borne by all operators and benefactors of space systems. Recent expert remarks have emphasized that the co-orbital ASAT potential of such systems is a more salient concern than claims about boost-phase interception. This is because the co-orbital potential is more feasible to realize than an effective boost-phase interception, arguably making space-based interceptor systems a more immediate threat to the space environment and space-based infrastructure.
The extension of human activity into cislunar and lunar space introduces not only new operational and governance challenges but also new layers of a security dilemma. As States and private actors aspire towards sustained presence beyond Earth orbit, even scientific missions may generate competitive insecurity. The orbital dynamics of the cislunar region, characterized by weak stability zones and sparse situational awareness coverage, further heighten uncertainty about intent. This intersects with a broader and enduring feature of outer space activity, its dual-use and dual-purpose dilemma. Dual-use describes the simultaneous or overlapping use of a technology for civilian and military applications. Dual-purpose refers to systems that can be repurposed from their stated function to serve different (potentially aggressive) ends. In space, these dilemmas are particularly acute. The high cost of access, limited redundancy in infrastructure, and incentive structures that reward versatility of function mean that few actors can afford to develop purely single-use or -purpose systems. Civil, commercial and military missions therefore share technologies, launch infrastructure, and orbits thereby blurring distinctions of intent. Even technologies developed to enhance sustainability of the space environment can be reinterpreted as tools for interference or negation. These structural and financial realities make space uniquely prone to dual-nature ambiguity, where current mechanisms for generating transparency can help identify where and what an object is but cannot ensure the intent behind its use.
These are space-centric problems, rooted in the physics of orbital mechanics, the economics of commercial activity, and the ambiguity of dual-natured operations. They generate instability theoretically through fears of deterrence failure, but more concretely through system complexity, resource competition, and the absence of coordinated management. The nuclear lens explains why restraint matters, but not how to manage the collective action problems that now define orbital sustainability and space security overall.
A broader vision of space security governance
Progressing space governance requires moving beyond the assumption that nuclear stability is the highest good. It may remain a necessary condition, but it is no longer solely sufficient for the challenges that define today’s orbital environment. The persistence of nuclear deterrence logic driving future space security debates could have two consequences: it continues to centre great-power rivalry as the lens for all space governance, and it marginalizes the concerns of space nascent or non-spacefaring States whose priorities lie in access, sustainability and equitable benefit.
A more inclusive approach is needed to advance space governance, what we apply to the concept of prevention in PAROS matters. Prevention of an arms race should encompass not only prospective weapons deployments but also the competitive dynamics, postures and perceptions that precipitate arms racing. Practical steps towards this already exist. Transparency and confidence-building measures, endorsed by UNGA Resolution 68/50 (2013), encourage among other things information exchange on national policies, pre-launch notifications, and cooperative data sharing on space situational awareness. Yet, transparency without confidence can resemble deterrence signalling rather than reassurance. Turning transparency into dialogue—through sustained communication and reciprocal understanding—is what transforms procedure into prevention, especially if routed through structured consultations and due-regard obligations already embedded in the Outer Space Treaty.
Equally vital are non-interference pledges. Commitments to avoid actions that could degrade satellites supporting nuclear command and control, but also those essential to humanitarian and civilian functions offer substantive starting-off points for extending restraint beyond strategic assets to the systems that sustain human security.
Finally, diplomacy, dialogue and cultural exchange remain essential for sustaining stability in space. Historical arms control progress depended on the continuous contact among scientists, diplomats and policymakers who learned to interpret each other’s signals. In strategic terms, patience is not passive. It reflects restraint built through familiarity, shared understanding, and confidence in the other’s intentions. In the space environment, where there may be countless opportunities for misinterpretation, nurturing such patience is difficult yet indispensable. Mechanisms to promote understanding and patience do exist. The Outer Space Treaty’s provisions for consultation, due regard, and information-sharing offer avenues for enhancing trust and restraint, provided States find the political will to use them and translate legal commitments into State practice. The same holds for multilateral bodies such as the Conference on Disarmament and the UN General Assembly; their value in trust building is determined not by their existence but by the seriousness and sincerity with which States participate.
The early treaties of the space age created a durable foundation for preventing nuclear conflict in orbit or on Earth. Their logic of restraint remains vital. Yet, six decades later, the space environment they helped stabilize has evolved into something far more complex. Recognizing the persistence of nuclear fragility is essential. Threats to early-warning satellites and NC3 systems still embody the sensitivities and danger of deterrence failure. The space environment’s vulnerabilities, encompassing debris, congestion, expansion beyond Earth orbit, and the blurred lines of dual-use development, show that effective governance must now pursue sustainability alongside stability. If nuclear deterrence logics once tried to preserve peace by managing fear and uncertainty, the next generation of governance must preserve peace by managing interdependence. Protecting nuclear systems should be the floor, not the ceiling, for a governance approach that recognizes the broader interconnections of security, sustainability and equity in space.
The author would like to thank Andrey Baklitskiy, Sam Hickey, Almudena Azcárate Ortega, Pavel Podvig, and James Revill for their expert review and feedback.
