IHL Application on the Potential Use of Weapons in Outer Space

by Divya Sharma, Student at University of Kent


Since the 1950s, with the development and successful launch of different spacecraft
such as satellites, humankind began to enter the vast outer space. The space is
extensive and boundless, and it can provide us a wide field of vision. Many countries
explored outer-space for military purposes from the start. In this article we look into
IHL rules surrounding outer space warfare.

While free from national sovereignty and outside national jurisdiction, outer space is never and should not be a lawless space. Under the international community, there are not many laws that maintain the sanctity of outer space. The international legal system has made negligible progress in implementing the laws specific to outer space since the Moon Agreement in 1979 at the United Nations (UN) forum. Apart from the privatization and commercialization of outer space, another serious challenge of potential armed conflict in outer space poses a real threat and demands a serious interest in the international community. [1] 

The current treaties and resolutions that address the duties and responsibilities of member states as regards their activities in outer space are as follows – 

Resolution 75/36, “Reducing space threats through norms, rules and principles of responsible behaviours” adopted by the United Nations (UN) General Assembly on 7 December 2020. This resolution outlines the responsibilities of member states towards the use of outer space. The resolution primarily encourages member states to study existing and potential threats and security risks in space systems, including those arising from actions, activities in outer space or on earth. [2] It also requests the Secretary-General to seek the views of Member States on the issues and submit a substantive report, with an annex containing these views, to the General Assembly for further discussion by member states on the same. [3]

The Outer Space Treaty (Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and other Celestial Bodies (1967). Article IV of the Outer Space Treaty prohibits the placement in the orbit of objects carrying nuclear weapons or other weapons of mass destruction, the installment of such weapons on celestial bodies and the stationing of such weapons in outer space in any other manner. 

There are no specific rules which directly recognize the norms regarding the armed conflict in outer space. The existing treaties and resolutions fail to address all the legal issues related to the armed conflict in outer space. With no specific legal instrument stating these rules, it is important to look into the existing international rules and norms that can apply to outer space’s environment. We will refer to the existing International humanitarian law and its rules that apply to the armed conflict in outer space. [4]

Traditionally IHL is recognized to be applied only on the military operations conducted on the ground. Still, with new technological advantages, the new avenues of military operations are used by the state actors and non-state actors in the present day scenario, such as drones warfare and cyber warfare. Outer space is due to become a new battlefield for armed conflicts soon. 

IHL is an important law that can be applied to all forms of warfare and weapons. As ICJ has recalled that the established principles and rules of IHL applicable in armed conflict apply “to all forms of warfare and all kinds of weapons, those of the past, those of the present and those of the future” [5]

For the application of IHL, it is important to establish the requirement of armed conflict in outer space, which brings us to the concept of armed conflict in outer space. 

Armed conflict in outer space can only be conditioned if it reaches the threshold of space militarisation, where the parties in the armed conflict can use force in outer space. It is important to maintain a difference between space weaponization and space militarization. Where space weaponization is related to “the placing in outer space for any length of time any device designed to attack man-made targets in outer space and/or in the terrestrial environment”, and space militarisation relates to “the use of outer space by a significant number of military spacecraft”. [6]

Under the realm of space militarisation, it is important to look into whether the concept of ‘attack’ according to IHL rules fits in the space context. Under Article 49(1) of AP I, the Attack is defined as an “act of violence against the adversary, whether in offence or defence.”

Space militarization can include two types of actions or activities. Firstly, the military use of satellite for image surveillance, electronic reconnaissance, marine monitoring, meteorological observation, telecommunications, early warning and navigation, which can support and strengthen the effectiveness of ground-based conventional weapons and military operations and secondly, the development and installation of space-based weapons to attack or destroy the target on the earth, at sea or in airspace, or interfere with its normal operation, or the development and installation of ground-based space weapons to attack or destroy the target in outer space or interfere with its normal operation. [7] It can be said undoubtedly that the space militarisation that can cause physical damage in space or earth would amount to an ‘attack’ according to the IHL rules. Despite the clear-cut situation, few scenarios can be difficult to ascertain the threshold of ‘attack’ according to IHL rules. For instance, self-destruction of one’s own satellite (China 2007 ASAT test) would amount to an armed conflict or not. The position on this is not very clear, but two arguments can be made in this context. On the one hand, standing alone, destruction of one’s satellite cannot amount to the Attack as per the IHL rules, but on the other hand, if the self-destruction operation is designed to generate orbital debris that can lead to the destruction of the enemy’s satellite (object of Attack in IHL terms) in the outer space that can qualify as an attack according to IHL rules. [8]

As already discussed currently, there are no specific rules directly related to the application of IHL on space warfare. However, the fundamental rules applicable to traditional wars apply equally to space warfare.

  • Principle of limitation – Article 35(1) of the Protocol Additional to the Geneva Convention IV of 8 June 1977 (Protocol-I) provides that “in any armed conflict, the right of the Parties to the conflict to choose methods or means of warfare is not unlimited“. These same rules naturally apply in space warfare as similar to the traditional form of wars. New types of space weapons, such as space-based kinetic weapons, which may cause severe damages, though small in scale, shall be excluded from the scope of possible weapons for armed conflict. [9]
  • Principle of distinction – It is a cardinal principle under the IHL and customary international law. Under this principle, there are two rules; firstly, the parties to an armed conflict must distinguish between civilians and combatants and can direct attacks against combatants only. Civilians (all who are neither combatants nor take direct part in hostilities) are protected under the IHL regime. Relevant to the space warfare article 52(2) of AP I clarifies that the objects may only be attacked if, “by their nature, location, purpose or use they make an effective contribution to military action and their total or partial destruction, capture or neutralization, in the circumstances ruling at the time, offers a definite military advantage” to the attacker. [10] Some difficulties can arise in distinguishing civilian and military objects due to the dual nature of the satellites. Furthermore, satellites for civil and commercial uses are also, in some cases, used for military purposes, which makes the distinction harder during an armed conflict. In these cases, according to Article 52(3) of Additional Protocol I to the Geneva Convention, in case of doubt whether a satellite which is normally dedicated to civilian purposes is being used to make an effective contribution to military action, it shall be presumed not to be so used. The parties cannot automatically assume that any satellite that appears dubious during an armed conflict may be subject to a lawful attack. Similar to the distinction between civilian and military objects, the issue arises between the distinction between the technical personnel or the astronaut operating the spacecraft and a combatant. According to Article 50(1) of Additional Protocol I to the Geneva Convention, in case of doubt whether technical personnel other relevant logistics support staff is a civilian, that person shall be considered to be a civilian. [11]
  • Principle of proportionality – This principle prohibits indiscriminate attacks by both parties during an armed conflict. Any attack which would be excessive concerning the concrete and direct military advantage anticipated can amount to an indiscriminate attack. Under an indiscriminate attack, a belligerent is not actively trying to attack civilians or civilian objects but instead acts recklessly, disregard such consequences. The prohibition of indiscriminate attacks does not amount to the complete prohibition of kinetic weapons. Still, it would amount to the precautions taken by the parties to minimize the negative consequences of an attack. Nuclear weapons and weapons of mass destruction prohibited by the limitation principle are similarly not allowed under this principle in the situation of armed conflict in outer space. More relevant to outer space, the threshold of indiscriminate attacks can be speculated according to the potential effects to the space debris. Debris-generating events can vary from case to case basis according to which it can be decided whether an attack is indiscriminate according to this principle. For instance, in 2019, India’s ASAT missile test wasn’t considered a violation of International law by Germany despite the statement of the NASA administration that this particular test increased the risk of small debris hitting the International Space Station by 44 per cent. [12]

In the concluding remarks, it is important to address that despite applying IHL rules and norms in outer space, there is an immediate need to make rules and laws specifically related to the armed during outer space. With all the technological advancements and unique physics of that domain, the traditional IHL cannot blame the parties and cannot fix the accountability of their actions in outer space. 

Disclaimer – All views and opinions expressed in this article are personal and belong solely to the author(s) and do not necessarily represent those of the LAABh Foundation or the individuals and institutions associated with LAABh Foundation.


[1] Yun Zhao, Armed Conflict in Outer Space: Legal Concept, Practice and Future Regulatory Regime, Space Policy 48 (2019) 50-59

[2] UN General Assembly, UN Doc. A/RES/75/36, 7 December 2020, para. 5.

[3] ibid. para 6.

[4] Supra note 1

[5] International Court of Justice, Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 8 July 1996, para. 86.

[6] Matthew Mowthorpe, in: The Militarization and Weaponization of Space, vol. 1, Lexington Books, New York, 2004.

[7] Supra note 1

[8] Michael Schmitt and Sqn. Ldr. Kieran Tinkler, War in Space: How International Humanitarian Law Might Apply, Just Security < https://www.justsecurity.org/68906/war-in-space-how-international-humanitarian-law-might-apply/ >

[9] Supra note 1

[10] Supra note 8

[11] ibid.

[12] ibid.

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