Military operations in space

As the role of space systems in military operations during armed conflict increases, the likelihood of these systems being targeted also increases. Current and future threats to space systems include electronic warfare, cyber operations and directed-energy operations; they also include the use of orbit-based and ground-based anti-satellite weapons or other counter-space military capabilities, such as harmful in-orbit rendezvous and proximity operations.

Space systems, particularly navigation, communications and remote-sensing satellites, play an indispensable role in critical civilian infrastructure, especially in the energy and communications sectors. These sectors enable the provision of the essential services on which civilians depend, such as food supply, water, electricity, sanitation, waste management and health care. 

Space systems also contribute to humanitarian relief operations and emergency responses. Additionally, space systems are critical to the functioning, protection, safety or maintenance of certain objects and people specifically protected under international law. Disrupting or destroying space systems carrying out such functions could have far-reaching consequences for the civilian population, including humanitarian organizations.

Whatever military activities or operations take place in outer space are constrained by existing international law.

The Outer Space Treaty recognizes the common interest of all mankind in the exploration and use of outer space for peaceful purposes. Article IV prohibits placing in orbit objects carrying nuclear weapons or other weapons of mass destruction, installing them on celestial bodies and stationing them in outer space in any other way.

The Charter of the United Nations sets out when states may resort to force; it prohibits the threat or use of force, except as authorized by the United Nations Security Council under Chapter VII and in self-defence under Article 51.

International humanitarian law (IHL) establishes rules on the conduct of hostilities with the aim of limiting, for humanitarian reasons, the effects of armed conflict. It includes in particular the principle of distinction, the prohibition of indiscriminate and disproportionate attacks, and the obligation to take all feasible precautions to avoid, or at least to minimize, incidental civilian harm. 

In the ICRC’s view, these rules apply not only to kinetic (physical) operations against space objects, but also to non-kinetic operations that would disable space objects without necessarily damaging them physically, such as cyber warfare. 

When assessing the lawfulness of such attacks, all foreseeable direct and indirect incidental harm or damage to civilian objects must be considered, including when targeting a space object used for both military and civilian purposes. The risk of creating debris, and its indirect effects, should also be considered when applying these rules. IHL also generally prohibits weapons that cause superfluous injury or unnecessary suffering and are indiscriminate by nature, as well as a number of specific types of weapon.

The law of neutrality regulates relations between belligerent states and neutral states in wartime. Like IHL, it also serves to mitigate and contain the adverse effects of an armed conflict.

The fact that international law, including IHL, constrains wartime military operations in, or in relation to, outer space neither encourages the weaponization of outer space nor legitimizes hostilities in outer space.

Given the risk of significant harm to civilians, states should consider the potential humanitarian consequences when taking any decision, at national and multilateral levels, on military operations in relation to outer space. States may decide to set general prohibitions or specific limits with regard to weapons, hostilities or other military operations in relation to outer space. They may do so for a range of reasons, including humanitarian ones, as they did in the Outer Space Treaty. If new legally binding instruments or other norms, rules and principles are to be developed, they must be consistent with and should build on and strengthen the existing legal framework, including IHL.