Regulating Conflict in Outer Space: Law at the Final Frontier
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War Above Us
It may still surprise us to learn that the first “space war” was fought over three decades ago. During the 1991 Gulf War, satellites enabled precision navigation, intelligence gathering, communications, and missile defence.[i] The conflict was not fought in space, but it was undeniably fought through it.
Today, that reliance has deepened. Modern military operations depend fundamentally on space-based infrastructure.[ii] GPS systems underpin navigation. Satellites sustain global communications. Intelligence, surveillance, and reconnaissance rely on orbital technologies. As a result, outer space is no longer a distant frontier of exploration - it is a critical domain of warfare.
This shift has not gone unnoticed. NATO has formally recognised space as an operational domain.[iii] The United States has established a Space Command and Space Force.[iv] Australia’s 2020 Defence Strategic Update identifies assured access to space as central to national security.[v] Across the globe, States are investing in satellite constellations, counter-space capabilities, and space control programs.
The question is no longer whether conflict may extend into space. It is how the law will regulate it when it does.
The Illusion of a Legal Vacuum
At first glance, outer space appears to exist beyond the reach of traditional legal frameworks. Unlike land, sea, and air, there is no dedicated regime governing armed conflict in space. The core treaties of international humanitarian law (IHL), including the Geneva Conventions, were not drafted with orbital warfare in mind.[vi]
Yet to characterise space as a legal vacuum is misleading. IHL is fundamentally concerned with regulating the conduct of hostilities wherever they occur. Its principles - distinction, proportionality, necessity, and humanity - are not confined to geography. They are designed to apply “in all circumstances,” including new technological and operational domains.[vii]
The Outer Space Treaty of 1967 reinforces this position.[viii] While it prohibits the placement of weapons of mass destruction in orbit, it does not ban conventional weapons or military activities more broadly. Instead, it requires that space activities be conducted in accordance with international law, including the United Nations Charter.[ix]
Accordingly, the use of force in space - whether through satellite attacks or space-based weapons - falls within the existing legal framework governing armed conflict. The real challenge is not the absence of law, but the difficulty of applying it.
Distinction in a Dual-Use Domain
One of the central principles of IHL is distinction: the obligation to differentiate between civilian objects and military objectives.[x] In the space environment, this principle becomes exceptionally difficult to operationalise.
Most space infrastructure is inherently dual-use. Satellites that enable civilian communications, banking systems, and internet connectivity may simultaneously support military operations. A single satellite can service multiple users across different jurisdictions, blurring the boundary between civilian and military functions.
This raises a critical question: when does a civilian satellite become a lawful military target?
The answer is not straightforward. Targeting such systems risks disrupting essential civilian services on a global scale. The destruction of a communications satellite, for example, may impair emergency services, financial transactions, and everyday connectivity far beyond the immediate theatre of conflict.
In this context, the principle of distinction is strained by the very architecture of modern space systems. It requires legal decision-making in an environment where categories are no longer clear.
Proportionality and the Problem of Debris
If distinction is uncertain, proportionality is even more complex. Under IHL, attacks must not cause harm to civilians that is excessive in relation to the anticipated military advantage. In space, assessing that balance is uniquely challenging.[xi]
The most significant issue is space debris. Kinetic attacks on satellites - such as anti-satellite (ASAT) missile strikes - can generate thousands, if not millions, of fragments.[xii] These fragments travel at extreme velocities and may remain in orbit for years or decades, posing ongoing risks to other space objects.
The consequences are not confined to the initial target. Debris can trigger cascading collisions, known as the Kessler Syndrome, potentially rendering entire orbital regions unusable.[xiii] Such outcomes would not only affect military operations but also disrupt civilian infrastructure globally.
Unlike terrestrial warfare, where damage is often geographically contained, harm in space is diffuse, persistent, and unpredictable. Evaluating proportionality in this context requires consideration of long-term environmental and societal consequences - factors that traditional IHL assessments were not designed to address.
The Expanding Arsenal
Compounding these challenges is the rapid development of counter-space technologies. States now possess a diverse array of capabilities, including:
● Kinetic ASAT weapons capable of destroying satellites[xiv]
● Co-orbital systems designed to collide with or disable targets[xv]
● Electromagnetic and radiation-based weapons[xvi]
● “Soft-kill” technologies such as cyberattacks, jamming, and laser dazzling[xvii]
Many of these methods do not produce immediate physical destruction but can disable systems in ways that are difficult to detect or attribute. Cyber operations, for instance, may interfere with satellite functionality without leaving clear evidence of an attack.
This raises further legal uncertainty. What constitutes an “attack” in space? Does non-kinetic interference fall within the scope of IHL targeting rules?
The answers remain contested. As technology evolves, the gap between legal categories and operational realities continues to widen.
Towards a Normative Framework
Given these uncertainties, calls for new treaties governing space warfare have gained traction. However, geopolitical realities make comprehensive agreements unlikely in the near term.
Instead, attention has turned to developing non-binding norms and interpretive guidance. One prominent initiative is the Woomera Manual, a collaborative project involving universities, governments, and international organisations.[xviii] The Manual seeks to articulate how existing international law applies to military space operations across peacetime, crisis, and armed conflict.
Such efforts are significant. They provide clarity where formal law is silent and contribute to the development of state practice. Over time, these norms may shape customary international law and influence how States interpret their legal obligations.
In this sense, the regulation of space conflict is likely to evolve incrementally, through interpretation and practice rather than formal codification.
Law Before the Conflict
The expansion of warfare into outer space is no longer a distant possibility. It is an emerging reality shaped by technological capability and strategic necessity. Yet the legal frameworks governing this domain remain underdeveloped and uncertain.
International humanitarian law provides a foundation, but its application in space is far from straightforward. Principles designed for terrestrial conflict must now operate in an environment defined by dual-use infrastructure, global interdependence, and long-term environmental risk.
The challenge is not simply to apply existing law, but to interpret it in ways that preserve its humanitarian purpose. If conflict does extend beyond Earth, the stakes will be global - not only for military actors, but for the civilian systems that underpin modern life.
The task, therefore, is urgent. Law must not follow conflict into space. It must anticipate it.
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References
[i] Steven van de Put and Anne-Rixt E Siemensma, ‘A Giant Leap for Humankind: Bridging Space Law and International Humanitarian Law*’ (2024) 62(1) The Military Law and the Law of War Review 31.
[ii] Yun Zhao and Shengli Jiang, ‘Armed Conflict in Outer Space: Legal Concept, Practice and Future Regulatory Regime’ [2019] Space Policy.
[iii] Steven van de Put and Anne-Rixt E Siemensma, ‘A Giant Leap for Humankind: Bridging Space Law and International Humanitarian Law*’ (2024) 62(1) The Military Law and the Law of War Review 31.
[iv] Yun Zhao and Shengli Jiang, ‘Armed Conflict in Outer Space: Legal Concept, Practice and Future Regulatory Regime’ [2019] Space Policy.
[v] Department of Defence (Australia), 2020 Defence Strategic Update (2020), 38.
[vi] Christian Jorgensen, "Old" Law for a "New" Frontier: The Sufficiency of International Humanitarian Law in
Outer Space, 57 Case W. Res. J. Int'l L. 343 (2025).
[vii] Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I), opened for signature 8 June 1977, 1125 UNTS 3 (entered into force 7 December 1979), art 51.
[viii] Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, opened for signature 27 January 1967, 610 UNTS 205 (entered into force 10 October 1967) art IV ('Outer Space Treaty').
[ix] Charter of the United Nations opened for signature 26 June 1945, XV UNCIO 335 (entered into force 24 October 1945).
[x] Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I), opened for signature 8 June 1977, 1125 UNTS 3 (entered into force 7 December 1979), art 48.
[xi] G. Blair Kuplic and Jonathan Sawmiller, ‘Humanity on the Final Frontier: Challenges in Applying International Humanitarian Law to Modern Military Space Operations’ [2024] International Review of the Red Cross 1.
[xii] Chris O’Meara, ‘Anti-Satellite Weapons and Self-Defence: Law and Limitations’ 249 <https://ieeexplore.ieee.org/abstract/document/10685637/>.
[xiii] Amrith Mariappan and John L Crassidis, ‘Kessler’s Syndrome: A Challenge to Humanity’ (2023) 4 Frontiers in space technologies.
[xiv] Stephen G Robison, ‘Legality of Non-Kinetic ASAT Weapons: A US Perspective on How Technology Outpaces Law’ (2022) 47(Issue 4/5) Air and Space Law 491.
[xv] Chris O’Meara, ‘Self-Defence in Outer Space: Anti-Satellite Weapons and the Jus Ad Bellum’ [2025] Leiden Journal of International Law 1.
[xvi] Bastiaan Smit, ‘The Security Dilemma in Earth Orbit: A New Space Arms Race’ (2022).
[xvii] Kartik Bommakanti, ‘“Soft Kill” or “Hard Kill”? The Requirements for India’s Space and Counter-Space Capabilities’ (Occasional Paper No 224, Observer Research Foundation, 2019).
[xviii] Cassandra Steer, ‘The Woomera Manual: Legitimising or Limiting Space Warfare?’ in Nikki Coleman and Stephen Coleman (eds), Military Space Ethics (Howgate Publishing, forthcoming, 2021) ANU College of Law Research Paper No 21.5.