The Legality of Intermingling Military and Civilian Capabilities in Space

by | Oct 17, 2022

Intermingling in space

The United States’ practice of intermingling national security space functions with commercial space capabilities and services has come under fire. Professor David Koplow, in an article entitled “Reverse Distinction: A U.S. Violation of the Law of Armed Conflict in Space,” argued that such intermingling violates the obligation under the law of armed conflict (LOAC) to protect civilian objects against the effects of attack. The argument is getting attention. In February, Air Force Magazine wrote about the article’s indictment of U.S. policy and in April, Professor Koplow presented his argument at the United States Space Command Legal Conference. The next month, he again made his case during a meeting of the United Nations’ Open Ended Working Group on Reducing Space Threats. As the reach of his argument increases, so does the need for a response.

I disagree with Professor Koplow’s conclusions for two reasons. First, intermingling is justified by genuine military necessity. Second, State practice lends no support to Professor Koplow’s thesis but instead supports the opposite conclusion.

“Reverse Distinction”

“Reverse Distinction” claims the deliberate intermingling of civilian and military space assets and functions violates the obligation to take precautions against the effects of attack. This duty is grounded in the LOAC principle of distinction.

Simply put, the principle obligates parties in an armed conflict to distinguish military objectives from civilian persons and objects. The attacking party honors this principle by taking precautions to spare civilians, as articulated in Article 57 of Additional Protocol I to the Geneva Conventions (AP I). Conversely, parties that are the object of attack must take precautions of their own. The passive precautions principle obligates parties to take feasible precautions to separate their own civilian persons and objects from military objectives so as to minimize harm to civilian persons and objects. Professor Koplow calls this duty “reverse distinction.”

The duty is most clearly articulated in Article 58, AP I. The International Committee of the Red Cross’s (ICRC) commentary observes that the duty extends to peacetime, when many feasible precautions must be implemented. By this reading, the obligation attaches prior to the start of an armed conflict.

The United States is not a party to AP I but does recognize many of its principles as obligatory under customary international law, including the principle of passive precautions. Accordingly, the DoD Law of War Manual declares, “[o]utside the context of conducting attacks (such as when conducting defense planning or other military operations), parties to a conflict should also take feasible precautions to reduce the risk of harm to [its own] protected persons and objects from the effects of enemy attacks.”

Assessing Feasibility

The obligation to take passive precautions is not absolute. It requires only what is feasible. The DoD manual describes feasible precautions as “those that are practicable or practically possible, taking into account all circumstances ruling at the time, including humanitarian and military considerations.” According to Geoffrey Corn, “[t]he feasibility qualifier would logically turn on considerations of military necessity.” Therefore, intermingling of military and civilian objects is permissible only when “justified by genuine military necessity.”

Military necessity is not the same as being necessary under the immediate circumstances. As the DoD manual explains, “In evaluating military necessity, one may consider the broader imperatives of winning the war as quickly and efficiently as possible.” These considerations reflect the broad notion of military necessity found in Article 14 of the Lieber Code, which defines military necessity as those measures which are “indispensable for securing the ends of the war.” Accordingly, intermingling can be consistent with the obligation to take feasible precautions if the true motive is to achieve a credible and legitimate military requirement necessary to achieve the broad imperative of winning the conflict as efficiently as possible.

However, a legitimate military necessity “would not include exploiting the presumptive protection” of civilian property. To illustrate this distinction, Corn considers the military use of a church steeple. If the steeple is needed for the vantage point it provides, then that use is legitimate because it has an objectively credible justification rooted in military necessity. If the steeple is used despite the availability of a more ordinary civilian structure such as a vacant apartment building, or even a military structure such as a watchtower that offers the same vantage point, the motivation for using the steeple may be considered illegitimate. An illegitimate motivation to impede an enemy attack can be logically inferred, according to Corn, by the ready availability of alternate options that might mitigate risk to civilian property.

Differing interpretations of military necessity are to be expected. David Luban observes a “two-cultures problem” grounded in competing premises. One premise holds the purpose of the laws of war is to “give full sway to military necessity and protect civilians (only) against military excess.” Adherents to this view read treaties “narrowly and formalistically under the assumption that States give up as little as they could when negotiating them.” The other premise holds that the purpose of the laws of war is “to protect civilians, even at cost to military effectiveness.” Adherents to this view interpret treaties “to fill gaps in the protection of civilians.”

Reconciling the competing premises requires taking them both seriously. The two cultures must learn to live with each other. This means not only taking civilian interests into account, but also respecting what Luban calls the principle of “Taking Necessity Seriously.”

Taking Necessity Seriously

One of my disagreements with “Reverse Distinction” is that it does not take military necessity sufficiently seriously. It argues that the United States’ practice of intermingling in space violates the passive precautions obligation because it is motivated by a desire to “complicate the task” of an adversary that might seek to attack U.S. national security satellites. But complicating the task of the enemy cannot be assumed to be illegitimate. Any action that provides a military advantage necessarily “complicates the task” of the adversary to counter that advantage. Challenging an adversary to overcome a military advantage is distinguishable from exploiting civilian objects to complicate the adversary’s proportionality calculation. Recall that using the church steeple for the vantage point it provides can sometimes be legitimate; this is true even if it complicates the enemy’s task. The real question, then, is whether the motivations for complicating the task of the adversary are grounded in legitimate military necessity.

“Reverse Distinction” recognizes that some motivations for intermingling could be legitimate. However, it argues that if a “side-effect” of intermingling is “complicating the challenges confronting any enemy (anti-satellite) program,” then any purportedly legitimate justification will be nothing more than an “illegitimate ploy” or a “feasibility subterfuge.” Here, again, complicating matters for the enemy is assumed to be an illegitimate justification. Not seriously considered is the possibility that intermingling could have this effect yet still have a credible justification of military necessity.

In effect, “Reverse Distinction” reduces the feasibility analysis to a single factor test in which intermingling equates to illegality. Intermingling is always unlawful and military necessity is not seriously considered. Particularly for those who subscribe to the principle of “Taking Necessity Seriously,” this approach falls short.

The Case for Lawful Intermingling

When the feasibility analysis takes military necessity into account – which it must – then the case for lawful intermingling in space becomes compelling. Put simply, intermingling in space offers real, legitimate, and significant military advantages, and is therefore justified by military necessity.

Military activities everywhere rely heavily on capabilities made possible by satellites in space. Space-based capabilities, such as remote sensing and satellite communications, enable the joint force to perform core functions in all domains. Any advantage that can be gained through these space capabilities will pay essential dividends to military operations. This is particularly true in modern warfare, where success will depend on decision superiority: the ability to collect, process, and share information to make decisions better and faster than adversaries. Indeed, the Department of Defense has developed an entire strategy initiative called Joint All-Domain Command and Control (JADC2) around this concept.

Decision superiority requires satellites, both military and commercial. The Space Development Agency (a DoD agency soon to transition to the Space Force) is developing a devoted military space architecture that will serve as the linchpin of JADC2. Known as the transport layer, it will comprise 300 to 500 satellites in Low Earth Orbit able to “provide assured, resilient, low-latency military data and connectivity to the full range of warfighter platforms.” This is often referred to as a “sensor-to-shooter” capability.

Commercial satellites will complement the Space Force’s transport layer, effectively making it a hybrid architecture. Commercial satellite communications will be necessary to ensure sufficient capacity, and the Space Force is studying how much demand can be met by commercial satellites. Commercial imagery will also boost the architecture’s military capabilities. The Space Development Agency has already signed a contract with Capella, a commercial synthetic aperture radar satellite operator, to plug its data directly into the transport layer and “would love to do that with all commercial providers.”

The motivation for intermingling in space is evident: intermingling offers a legitimate military advantage that a military space architecture alone cannot provide. No matter how large and capable a purely military satellite architecture may be, complementing it with commercial constellations inherently enhances the capabilities and resiliency. The United States Space Command’s Commercial Integration Strategy sums up this approach when it calls for integration of commercial services through contracts and leases in order to “mitigate capability gaps” and “improve space architecture resiliency.”

Recent events in Ukraine demonstrate the significance that intermingling can have in a successful military campaign. One example is the value of commercial communication satellites. Since Russia’s invasion, Ukraine has become reliant on SpaceX’s Starlink, a space system that links a constellation of satellites in Low Earth Orbit to portable ground terminals to provide internet broadband signals. Ukraine has taken advantage of Starlink, using it not only for civilian communication but also to operate drones combating Russian forces. According to one Ukrainian soldier, “Starlink is what changed the war in Ukraine’s favor. Russia went out of its way to blow up all our comms. Now they can’t. Starlink works under Katyusha fire, under artillery fire. It even works in Mariupol.”

Granted, the Ukraine example is not directly analogous to the United States’ intermingling strategy. Ukraine has little choice but to fall back on commercial satellite services in lieu of a dedicated and robust military space architecture, whereas the United States has been deliberate in its pursuit of a hybrid architecture. Nevertheless, the war in Ukraine validates the United States’ hybrid strategy. General James Dickinson, Commander of U.S. Space Command, commented, “I think what we’re seeing with Elon Musk and the Starlink capabilities [he is] providing is really kind of showing us what a mega constellation or proliferated architecture can provide … in terms of redundancy and capability.” Similarly, the Assistant Secretary of the Air Force for Space Acquisition and Integration testified to a Congressional subcommittee that “one lesson … [from Ukraine] is that by adding and integrating commercial capabilities … you are going to diversify your architecture and make it much more resilient, and so that has really been a great piece of the puzzle.” The United States needs this piece of the puzzle to maximize its military advantage and ability to achieve the broader aims of war as quickly and efficiently as possible.

Are these advantages sufficient to qualify as military necessity, or are they mere conveniences that are inadequate to justify the potential harm to civilians and civilian property? The importance of commercial space architectures’ contributions to military capabilities ought not be underestimated. In Ukraine, the advantages of intermingling have been indispensable to the war effort. Moreover, even if a robust all-military space architecture were to become available at great expense, it strains credulity to suggest that integrating that military architecture with commercial space capabilities would be a mere convenience. In a world where speed, data, and connectivity drive military operations in all domains, it is reasonable to conclude that intermingling will significantly contribute to the broader imperative of winning an armed conflict.

The Importance of State Practice

A second reason for disagreement is grounded in the role of State practice. “Reverse Distinction” omits any serious consideration of State practice and the sense of legal obligation that attaches to that practice (opinio juris). However, States have a crucial influence on how LOAC principles developed for one domain are translated to a different domain, like outer space. As Matt King and Laurie Blank observed, “the technology, physics, and geopolitics of space make tackling the contours and the sometimes domain-specific intricacies of general principles and customary international law a challenge.” Accordingly, State practice “will be a, if not the, significant determining factor.”

“Reverse Distinction” claims the United States’ practice of intermingling in space is a violation of the passive precautions principle, but it cites to no evidence that any State shares this interpretation. The justification offered for this omission is because the lack of actual warfare in space “means that there is precious little actual physical State practice to draw upon … in deriving the operational rules that might further inform future combat in space.” This justification is largely immaterial because the duty to take passive precautions is partly preventative in character. As the ICRC commentary affirms, passive precaution obligations extend to measures to be taken in peacetime. Moreover, combat need not occur in space to establish state practice in this area of law. Intermingling military and commercial space assets can and does affect combat operations in all domains.

State practice is full of examples of intermingling, and not just by the United States. Italy and South Korea have used SpaceX to launch military satellites. The United Kingdom’s 2022 Defence Space Strategy calls for increasing resilience through integration with commercial communications satellites. Australia’s 2022 Defense Space Strategy recognizes the need to leverage agreements not only with international partners but also with commercial entities for many space capabilities, and notes that the Australian Geospatial-Intelligence Organisation (AGO) “is progressively delivering sovereign space-based ISR capabilities including ground infrastructure to allow AGO direct and timely access to imagery from commercially owned-and-operated satellites.” Similarly, France’s 2019 Space Defence Strategy demonstrates its willingness to avail itself of “New Space” capabilities, and NATO’s 2022 space policy calls for the use of “[a]llies’ capabilities and, if necessary, trusted commercial service providers” to be leveraged to meet operational requirements. Far from avoiding intermingling, many States are increasingly embracing it as a military necessity.

The war in Ukraine offers additional evidence of States’ growing acceptance of intermingling in space during an armed conflict. The contribution of commercial satellites to Ukraine’s defense extends far beyond using Starlink for communications. The United States opened the commercial imagery pipeline to Ukraine. A Canadian company, with the approval of the Canadian government, answered the call to provide Ukraine with satellite imagery. A Finnish company, ICEYE, signed a contract to provide synthetic aperture radar imagery to Ukraine to support the war effort. The CEO of Hawkeye 360, a U.S. commercial operator of satellite clusters that can detect and geolocate radiofrequencies, “declined to say publicly what his company has been doing in the Ukraine area of operations” but does say, “[p]art of our value proposition very much is that the data that we produce is shareable, it’s exportable, it’s able to be provided to coalition partners on the battlefield.”


State practice does not support the view that the passive precautions principle prohibits intermingling in space either in peacetime or during armed conflict. Far from exploitative, intermingling in space is usually contractual and mutually beneficial. Commercial operators understand their satellites may become lawfully targeted, and they willingly accept this risk.

The humanitarian considerations are also different because damage to a civilian satellite – even if it is a satellite payload with an entirely civilian purpose – simply does not warrant the same concern to an attacker as damage to cultural property or loss of civilian life. As the DoD Manual says, “[i]n light of the humanitarian objectives of the law of war, the expected loss of civilian life … should be given greater consideration than the expected damage to civilian objects” and “expected damage to cultural property should be afforded greater consideration than expected damage to ordinary property.” The humanitarian considerations in space are not necessarily the same as those in other domains, and this informs how States view the application of LOAC principles in space.

As Michael Schmitt observes, in LOAC “military necessity exists in equipoise with the principle of humanity.” States, he argues, must make choices about whether and how to adjust treaties and practices when new circumstances call into question “the perceived sufficiency of a particular balancing of military necessity and humanity.” The advent of intermingling in space has presented States with such a choice. Their decision has not been to condemn the practice as illegal. Indeed, the evidence increasingly suggests States are willing to accommodate intermingling as part of the delicate balance.

Certainly, States and commentators may have misgivings about intermingling in space. Commercial satellites may become targetable military objectives. Questions about how the legal framework applies to targeted commercial satellites remain unanswered. Civilians are at risk of experiencing service outages, potentially with harmful consequences. States risk antagonizing adversaries like China, which is reportedly concerned about the security threat posed by a “militarized” Starlink constellation. Any of these concerns may prompt States to approach intermingling space strategies with caution and restraint. The question, however, is why they may feel cautious or restrained and whether the sentiment is grounded in a sense of legal obligation to comply with the passive precautions principle. Put another way, what is the evidence that States feel legally obligated to refrain from intermingling in space on the basis that intermingling cannot be justified by military necessity? “Reverse Distinction” makes a valuable contribution to the discourse, but unless and until States begin to oppose intermingling in space on a legal basis through their practices and expressions of opinio juris, assertions of illegality are premature.


John Goehring is a national security law attorney within the Department of Defense and a lieutenant colonel judge advocate in the U.S. Air Force Reserve. The views expressed here do not reflect those of the Department of Defense, the U.S. Air Force, or any other department or agency of the U.S. Government.


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