Can Starlink Satellites Be Lawfully Targeted?

by | Aug 5, 2022


In an earlier post, I discussed the special attribution regime in Article VI of the Outer Space Treaty (OST) and the risk of activities of commercial actors drawing States into existing armed conflicts. This analysis stemmed from Elon Musk providing Starlink services to Ukraine in order to fill in a communication gap for the Ukrainian military and its civilians after Russia destroyed key components of Ukraine’s internet infrastructure. The second part to this series will examine whether Russia may lawfully target Starlink satellites as a valid military objective under international law (as international law is expressly applicable to space by Article III of the OST) and what this would mean for the United States.

Starlink as a Lawful Target

The question of whether Starlink satellites are valid military objectives is an important one because States are paying attention to the Starlink system and its implications for future conflict. As noted in the earlier post, China’s People’s Liberation Army (PLA) has accused the United States of “militarizing” the Starlink program. More recently, the South China Morning Post reported that China must have the capability to destroy Starlink if it threatens their national security. The report was prompted by a paper published by researchers affiliated with China’s defense industry that proposed ways in which China could develop hard-kill and soft-kill capabilities for use against Starlink. China is no doubt acutely cognizant of the potential for Starlink to aid Taiwan, as it has aided Ukraine, in a possible future China-Taiwan armed conflict. Thus, the underlying legal question of possible characterization of Starlink as a military objective has broader implications than just in the context of the current Russia-Ukraine war.

Military Objective

Article 52(2) of Additional Protocol I (API), which reflects customary international law, sets forth the definition of a military objective. To qualify as such, Starlink must by its nature, location, purpose, or use make an effective contribution to (Ukraine’s) military action and its total or partial destruction, capture, or neutralization, in the circumstances ruling at the time, must offer (Russia) a definite military advantage.

In the Russia-Ukraine war context, these requirements are met: Starlink is being used to provide Ukrainian military forces with high-speed internet and communication, which effectively contributes to their military operations. For example, it has enabled interception of Russian battlefield communications, facilitated Ukrainian C2 and information operations, and assisted a Ukrainian drone unit to destroy Russian tanks. One Ukrainian soldier described Starlink as having changed the war in Ukraine’s favor. Denying Ukraine this capability would undoubtedly offer Russia a definite military advantage.

It is the agility of Starlink which sets it apart from its competitors. It is also an aspect that affects the legal analysis. There are currently over 2,000 functional satellites within the constellation and, as it operates in the low earth orbit (LEO), SpaceX is able to quickly replace a satellite if required. An attack on a single satellite is unlikely to cause anything more than a negligible or de minimus disruption to the system. Thus, it is difficult to see how an isolated attack on one Starlink satellite would provide definite military advantage.

For the purposes of this post, it will be assumed that an attack on Starlink will be sophisticated and broad enough to cause a measured degradation of the system. It will also be assumed that the attack will involve the use of lethal force because, so far, Starlink has continued to operate despite Russian jamming attempts, by dynamically changing its electromagnetic posture (a move described as “eyewatering” by the Pentagon). Russia has the capability to target satellites kinetically, as demonstrated by its direct-ascent anti-satellite mission (DA-ASAT) in November 2021 and by its rendezvous and proximity operations (RPO); the United States has assessed that a projectile fired from Russian satellite Cosmos 2543 could be used to target satellites.

The civilian use of Starlink has no bearing on it constituting a valid military objective, but a lawful attack must comply with the requirements of proportionality and the obligation to take precautionary measures.

Proportionality – Incidental Damage

By Article 51(5)(b) of API, any incidental loss of civilian life, injury to civilians or damage to civilian objects, or a combination thereof, must not be excessive in relation to the concrete and direct military advantage anticipated. In some circumstances, one may be able to separate an object into civilian and military components, and only target the military element. A communications satellite, however, is not severable in this way, and an attack would result in a loss of use of that satellites’ services for both military users as well as civilians.

The International Committee for the Red Cross (ICRC) published a report in which a group of international experts discussed the proportionality principle and concluded that while a dual-use object is a military objective, the impact of the attack on simultaneous civilian use or function (such as in the case of a bridge or an electricity station used for both military and civilian purposes) must also be taken into consideration in the assessment of proportionality. This position is consistent with the approach taken by the United States, as set out in the Joint Targeting Directive, (JP3-60, paragraph 6(2)(a)).

But only consequences that meet the standard set out in Article 51(5)(b), i.e. death, injury or destruction, will factor into the proportionality assessment. In some circumstances it will be foreseeable that the civilian loss of function will result in these consequences. Consider, for example, an attack against a power plant providing electricity that is used to operate hospitals and treat water and sewerage. Mere loss of internet services does not per se qualify as collateral damage in the proportionality analysis.

Synchronized attacks against the Starlink constellation could cause significant harm to civilians in those countries that do not have a backup system for their internet service, such as Tonga, which has relied on the Starlink service since the December 2021 tsunami for humanitarian operations and of course, Ukraine whereby the loss of service would impact its emergency services and civil defense warnings. The latter example is of particular importance in this case.

In sum, it is possible that the civilian loss of use caused by an attack against Starlink may cause collateral harm to the extent that it will feature in the proportionality assessment. However, even if the examples feature in the calculation that of itself is not a convincing argument that an attack would be excessive and fall afoul of the proportionality requirement due to the scale of concrete and direct military advantage Russia would garner by denying Ukraine this capability.

Proportionality – Indiscriminate Attacks

Article 51(4) prohibits indiscriminate attacks. This includes (a) where the attack is not directed at a specific military objective, or (b) where the attack employs a method or means of combat which cannot be directed at a specific military objective or, (c) attacks which employ a means or method of combat the effects of which cannot be limited and, as such, may strike military objectives and civilians and civilians or civilian objects without distinction

An attack against satellites within the Starlink constellation will introduce further debris into outer space. The most recent figures provided by the European Space Agency estimate that there are currently approximately 36,500 large (greater than 10 cm) pieces of space debris and 130 million smaller pieces. Orbiting debris travels at an incredible velocity and is likely to render any satellite that it collides with inoperable.

The debris resulting from an attack against a satellite cannot be controlled and it has long lasting consequences. China’s 2007 DA-ASAT demonstration against a single Chinese defunct weather satellite created approximately 35,000 pieces of debris. NASA predicted that this would remain in orbit for approximately 40 years. As recently as last year, the International Space Station (ISS) had to maneuver to avoid a collision with space debris. As there are currently no affordable means of cleaning up debris, these consequences are not easily mitigated.

To date, there have been a limited number of debris and satellite conjunctions, one example being a French satellite damaged by debris caused by an exploded French rocket in 1996. Therefore, an attack against a single satellite would be unlikely to fall afoul of Article 51(4)(c). However, an attack against the constellation would introduce an unprecedented amount of debris which would render collision avoidance unmanageable, and would therefore violate the prohibition against indiscriminate attacks.

Proportionality – Environmental Considerations

Article 35(3) of API prohibits the employment of means or methods of warfare which are intended, or may be expected, to cause widespread, long-term, and severe damage to the natural environment. Further, Article 55(1) requires that care be taken in warfare to protect the natural environment against widespread, long-term, and severe damage.

No definition is provided as to the scope of the “natural environment,” but Article II of the Environmental Modification Convention (ENMOD), of which both Russia and the United States are parties, includes outer space within the scope of the term environment. The 2016 ICRC commentary interprets “widespread” as meaning an area encompassing several hundred square kilometers, “long-lasting” as meaning a period of months, or approximately a season, and “severe” as involving serious or significant disruption or harm to human life, natural economic resources, or other assets.

Russia, being a State party to API, is bound by these prohibitions. The United States, as a non-State party, takes into account environmental considerations during targeting decisions, albeit to a much lower standard. JP3-60 (paragraph 8(b)) sets out:

It is generally lawful under the laws of war to cause collateral damage to the environment during an attack on a legitimate military target. However, the commander has an affirmative obligation to avoid unnecessary damage to the environment to the extent that it is practical to do so consistent with mission accomplishment.

The Nuclear Weapons Advisory Opinion affirmed that respect for the environment is one of the elements considered when assessing whether an action is in conformity with the principles of necessity and proportionality.

Cascading debris is a live issue whereby the debris in LEO is expected to multiply by a factor of five within this century. An attack which takes out hundreds of Starlink satellites within the constellation will introduce debris of such magnitude in an already congested area that it could jeopardize access to the LEO. Whether such environmental damage will reach the “widespread, long-term and severe” threshold is yet to be seen but, as debris from one ASAT is expected to remain for 40 years, debris created by the destruction of 2400 would likely to exceed a season and involve serious disruption to civilian services, it is certainly foreseeable.

Precautions in Attack

There are several requirements to take precautions in an attack, two of which would be pertinent to an attack against Starlink:

1. Take all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects (Article 57(2)(iii)).

2. When a choice is possible between several military objectives for obtaining a similar military advantage, the objective to be selected shall be that the attack on which may be expected to cause the least danger to civilian lives and civilian objects (Article 57(3)).

A viable alternative to a kinetic attack against Starlink would be jamming or spoofing. However, despite Russia’s advanced electronic warfare capabilities, it has so far failed to overcome Starlink. A co-orbital ASAT, which involves placing the weapon into orbit then maneuvering it into or near its target, would be less destructive than a DA-ASAT launched from Earth. Russia could also target the Starlink terminals in Ukrainian territory. However, the problem for Russia is that approximately 10,000 Starlink terminals have been shipped to Ukraine, and they are likely to be widely dispersed. Therefore, it may not be feasible target these terminals due to their amount and dispersion.


The United States is keen to avoid conflict spilling into outer space. In demonstration of this commitment, they unilaterally pledged not to conduct any further DA-ASAT tests and are also developing tenets of responsible space behaviors. However, States must also be cognizant of the risk of commercial satellite systems becoming valid military objectives, particularly where the State relies on that system for its own military activities. The US Army already has a contract with Starlink. Similarly, the USAF has funded testing of Starlinks interoperability with military aircraft under encryption, and further testing is ongoing with the contract being worth around $40 million per experiment. Starlink was also relied on during the US evacuation operations in Afghanistan. General Dickinson, head of US Space Command, has publicly acknowledged what Starlink offers in terms of capability – the potential military value that Starlink could provide to the United States is indisputable.

The Starlink constellation is a valid military objective but, as for Russia targeting it, a kinetic attack levied against an entire constellation would be of such a scale that it is difficult to imagine the attack would not run afoul of the principle of proportionality.

However, while Russia has not yet succeeded in deploying non-kinetic methods of attack in space, China is watching closely and already holds a robust arsenal of counterspace capabilities. Chinese defense-affiliated researchers have called for the development of vigorous countermeasures, including kinetic countermeasures, for use against Starlink. The United States military will wish to preserve and protect the utility of Starlink, and avoid a situation in which China employs such a capability.


Squadron Leader Tara Brown is a military professor at the Stockton Center for International Law at the U.S. Naval War College, where she co-teaches a course on Air, Space and Cyber Law.


Photo credit: SpaceX