The Importance of Revisiting Deterrence in the Space Domain
This essay is from the Security & Defence PLuS Emerging Voices Series, which highlights the next generation of scholars and practitioners shaping thinking on strategy, security, and defense. The series brings together perspectives from PhD candidates and early career researchers, grounded in the complex geopolitical realities of the 21st century.
The collection explores a “Latticework of Resilience” that connects often-overlooked sectors, such as subnational diplomacy and critical infrastructure inherent in agriculture security, to the core of national security. Taken together, the essays emphasize the importance of adaptive, multidisciplinary approaches to building resilience in an increasingly complex global environment.
The second event in the Emerging Voices series was held at King’s College London on 18 June 2026, a previous event took place at ASU and another will follow at UNSW. Watch the event recording: The Emerging Voices Series: Strategy, Security & Defence at King’s College London.
The UK’s long awaited Defence Investment Plan (DIP), published in late June 2026, reinforced the need for an Integrated Force, which includes investment in several domains such as digital, air, maritime and space. The document noted a strategic shift in terms of recognizing space’s importance as a “contested frontline” and the critical need to “deter threats” to sovereign interests in space. While this recognition is a welcome one, the DIP falls short in a number of areas on space, including in the continued reluctance to critically engage with the concept of “space deterrence”.
But this is not an issue unique to the DIP as several UK defense documents tout the importance of deterrence in the space domain but fail to expand on what this really means. Joint Doctrine Publication 0-40 (2022) contains a welcome subchapter on space and deterrence but limits its discussion to three overarching points and fails to delve deeper into some of the complexities that applying conventional understandings of deterrence to the space domain may raise. The latest Strategic Defence Review (SDR), published in 2025, suffers a similar issue, stressing the urgent need to improve the ability to “deter threats” to interests in space but with little detail.
This article aims to highlight the need for a more careful and considered approach to deterrence in space that goes beyond our conventional understanding of the framework. It argues that the three key pillars of deterrence – capability, credibility and communication – need to be applied with more nuance when formulating deterrence strategies for space. While a substantial discussion of this topic is beyond the scope of the paper, this piece serves as an introduction for those less familiar with deterrence theory to think more critically about the application of the concept to the space domain. Key concepts in security such as coercion, deterrence and bargaining are often misunderstood or misconstrued by practitioners, creating pitfalls in strategic planning and implementation of policy. Effective formulation of strategy for space deterrence will require practitioners to think more critically about these concepts.
Foundational Nuances in the Space-Deterrence Nexus
A primary, critical nuance to untangle in the space-deterrence calculus is unpacking what we actually mean when we discuss “space deterrence”. Space systems are often important for conventional deterrence, including intelligence, surveillance, target acquisition, and reconnaissance (ISTAR), and nuclear deterrence, through early warning satellite constellations and space-based command, control and communication (C3) systems. While there is some overlap, this does differ in many ways to a discussion of “deterrence in space,” which instead concerns countering threats to infrastructure and conflict in the domain itself.
Policy documents, such as the 2025 SDR and the 2026 DIP, all make more general reference to a need to “deter threats” to “interests” in space, but often in linkage to the role of space systems in conventional warfighting. The 2021 National Space Strategy went slightly further in highlighting the importance of “deter[ring] hostile activity against space systems, including the use of weapons in space”. The document also touches on the dual-use and dual-purpose nature of many space systems by noting that “space sustainability and space security must be considered alongside each other”. This is due to the fact that the domain consists of objects designed for both civil and military uses (dual-use) or those that may seem to have benign, civilian uses but could also be used for military means (dual-purpose) that can create interconnected issues of safety and security. The 2022 Defence Space Strategy offered similarly promising remarks with some engagement on the complexities of deterrence under Strategic Theme 1: Protect and Defend. This clarity is important but can still be expanded further, and future space strategy and defense documents on space must further contend with this foundational nuance to ensure clear and accurate deterrence policy on space.
It is also important to engage with discussions of deterrence by denial and deterrence by punishment. Deterrence by denial involves creating conditions that would make the target unlikely to succeed, thus deterring them from their original course of action. Deterrence by punishment, on the other hand, involves threatening severe costs should the target proceed with their indented action. For the space domain, deterrence by denial has become a central part of national strategy with countries like the UK inadvertently integrating denial into their deterrence posture through emphasis on resilience. While both approaches offer some merit and there is no perceivable predisposed value in one or the other, studies have suggested a mix of the two can offer a more comprehensive and effective approach to deterring in space. However, as discussed below, there are certain complexities that make enacting an integrated approach to deterrence more complex than it may appear at first glance.
Beyond the scope of this paper, but of no less importance, is also the discussion of the burgeoning private space sector. With Elon Musk’s SpaceX making up 65% of all active spacecraft in orbit as of 2026 and a planned 15-30,000 additional satellites under Starlink Gen2, private actors must be considered in the discussion of space deterrence.
Capability
In deterrence theory, capability concerns the capacity of the deterring power to respond decisively to a threat. It is one of the more straightforward tenets of deterrence, referring to the possession of forces or systems that can demonstrate might.
Space as a strategic domain spans vast orbits and geographies, and discussions on space can often fall into the trap of treating systems as distant, remote structures. This assumption can be dangerous in misconstruing the proximity of threats and leading to potential misunderstandings about just how vast and complex space systems are. Capabilities in space contain Earth-bound segments that must factor into conceptualizations of space deterrence. Satellites, for example, can often seem like far away objects stationed in orbit but are tied to ground stations on Earth that oversee the command and control of satellite architecture. Attacks on these ground stations can have significant consequences for space-based systems, as was witnessed in the Russian hack on Viasat ground infrastructure shortly before the invasion of Ukraine in 2022.
As mentioned earlier, there is also a dual-use and dual-purpose aspect to consider when discussing capabilities in space. A key example of this is on-orbit servicing, which is the act of performing technological upgrades, repairs, refueling, and/or inspections of satellites currently in orbit. These activities require the ability to undertake a rendezvous and proximity operation (RPO), where the servicing object would have to move closer to the satellite and perhaps even dock or berth in order to connect to the satellite. While this use is civil in nature, there are clear security concerns as the same technology could be used to get closer to satellites and listen in on or intercept signals, or in severe cases, physically interfere with the satellite. This potential capacity demonstrates the added complexities that space technologies present in discussions of capability in deterrence, as less obvious forms of infrastructure may need to be considered.
Credibility
The second pillar, credibility, refers to the will to impose costs on the target. More simply, it means that the deterring actor must demonstrate that they possess the ability to carry out the threat and bear any consequences to the target.
In the space domain, demonstrating resolve can come in a range of forms. On the sharper side, testing of weapons and anti-satellite (ASAT) capabilities can serve as a clear signal of pursuit of a credible deterrent and the ability to levy a threat. Following the successful completion of its kinetic ASAT test in March 2019, the Indian Government noted that “The capability achieved through the anti-satellite missile test provides credible deterrence against threats to our growing space-based assets”. Other options include alliances and partnerships, such as Multinational Force Operation Olympic Defender. The pact, consisting of Australia, Canada, France, Germany, New Zealand, the UK and the US, is committed to deterring aggression and retaining military advantage through shared capabilities.
The importance of demonstrating resolve in the space domain has been recognized in some UK publications, namely the Defence Space Strategy. The document notes that “credibility is not simply limited to capability; it must include our international alliances, commercial partnerships and the way in which we operate in the domain”. This is a significant step in strategic thinking but still falls somewhat below the standard of alliance partners like the United States, which is a lot clearer in tone about the nature of space threats and the need to respond.
Another aspect to consider and key to the demonstration of resolve in the event of an incident is attribution as the defender must be confident that they will not mistakenly escalate a situation by misattributing a loss as an attack. As such, attribution is a “necessary enabler of retaliation”. Equally, timelines are important and the defender will want to respond within an appropriate timeframe so as not to embolden the attacker. This balance can be difficult in conventional deterrence contexts, but the space domain adds an added layer of complexity to this issue. Space is host to a number of phenomena, such as weather events and naturally generated debris, and without adequate awareness and monitoring capabilities the potential for misinterpretation is high.
This is exacerbated by a lack of clear red lines and escalation dynamics in the domain. While recent confrontations in the domain, including in close calls between satellites and pursuit of some offensive capabilities, there is still little consensus about what constitutes as a red line in space conflict. This is exemplified by ongoing disagreements between nations about what constitutes as a space weapon. These fundamental disagreements mean that while an event in space may appear benign to one actor, to another it could be a severely escalatory incident. Examples include Russia’s assertion that any commercial space infrastructure or systems being used to aid Ukraine’s war effort was “a legitimate target for a retaliatory strike” in the eyes of the Russian state.
Communication
Key to demonstrating credibility and resolve is the third, sometimes overlooked, pillar of deterrence: communication. The ability to communicate and signal to the target the capabilities an actor possesses and its ability to exercise such capabilities is fundamental to effective deterrence. Communication can come in many forms, including as , noted by JD Fearon in his seminal work on the topic, such as “tying hands” (such as formal treaties and alliances) or “sinking costs” (such as mobilizing troops or conducting costly weapons tests).
Important to consider in any discussion of communicating is the role of perceptions. Championed through the work of Robert Jervis, this factor emphasizes that it is not so important what the defender communicates, but instead the way it is perceived and interpreted by the target as not all actors perceive an event in the same way.
A key example of this is the ongoing debate about President Trump’s proposed Golden Dome for America, which will reportedly include space-based kinetic interceptors. While Washington has emphasized that the Golden Dome is non-offensive and is being pursued for homeland protection, it has not been received in the same way by adversaries. Beijing has previously viewed Washington’s pursuit of missile defenses as a race for anti-satellite weapons and a clear pursuit of counterspace capabilities, threatening China’s operations and infrastructure in space and with clear consequences for earth-based capabilities also. On Golden Dome, the Foreign Ministry denounced the “strong offensive nature” of the project and argued that it would “heighten the risk of turning the space into a war zone and creating a space arms race”.
Moscow shares similar concerns, with Ministry of Foreign Affairs Spokesperson Maria Zakharova warning that Golden Dome would be “effectively turning outer space into a deployment area and an arena for military confrontation”.
Perceptions are often overlooked, especially in the space domain. None of the UK strategy and policy documents listed in this piece consider how certain positions may be interpreted by adversaries and while there is some significant headway, academic literature on perceptions in space activities is also relatively young. This is especially dangerous given that our adversaries are already steps ahead in strategic thinking in this area. The Chinese concept of weishe (deterrence/coercion) places importance on influencing a potential target’s perceptions and decision calculus and instead compelling it to adopt courses of action in line with to Chinese interests. Russia employs a similar strategy through its theory of reflexive control, a Soviet-era concept centered on the role of opponent perceptions. Of all the pillars discussed in the piece, communication is arguably one of the most important yet overlooked tenets of space deterrence.
Overall, it is clear that effective policy and strategy making on deterrence in the space domain must contend with a number of complexities. It is not enough to merely superimpose conventional understandings of deterrence to a domain that is rapidly changing in the character of its activities but also of the actors that operate within it.
