Precautions and Aerial Superiority or Supremacy


| Jun 5, 2024


In modern armed conflict, belligerents must control the air domain. Air supremacy or air superiority is a precondition for success in land and naval operations. Simultaneously, belligerents must exercise “constant care to spare the civilian population, civilians and civilian object in the conduct of military operations.” This raises the question whether there is a correlation between what the precautions requirement demands and the extent to which a belligerent has attained air supremacy/superiority.

If a belligerent fully controls the airspace over the battlefield, should that belligerent be subject to a corresponding obligation to exercise greater diligence in the targeting process? Our argument is that when a belligerent’s freedom of action in battlefield airspace is not restricted by enemy interference—that is, when a belligerent has achieved air superiority or air supremacy—the belligerent must exercise more care in planning and executing air operations, especially those with the potential to create harm among the civilian population and civilian objects.

Control of the Air

Military doctrine recognizes four levels of airspace control in air operations. The first level is air parity, a situation of aerial stalemate. At parity neither belligerent is able to obtain an advantage in the airspace. The current situation over Ukraine could be described as one of air parity: neither is able to overcome the enemy or use air to significant advantage. Neither Ukrainian nor Russian air forces has operational freedom, which drastically limits each side’s presence in hostile airspace.

The second level of  air control is a favorable air situation, when one of the belligerents has an advantage in aerial operations. In the context of the war in Ukraine, from time to time both Ukrainian and Russian air forces have had short windows of a favorable air situation. For example, each has exploited a gap in radar coverage over a certain area occurs, mostly due to successful suppression of enemy air defence or destruction of enemy air defence operations.

The third level of command of the air is air superiority. At this level, one belligerent’s control of the air space significantly degrades the aerial and anti-aircraft assets of the opposing belligerent. Control exists to the extent that the latter cannot effectively suppress the former’s air activities.

The final level of air control is air supremacy/air dominance. It involves one belligerent being completely unable to confront or interrupt the adversary’s aerial activities. Air supremacy is often associated with asymmetric conflict, when one the belligerents is technologically inferior and does not possess effective means of challenging the adversary’s air operations.

Establishing air dominance offers obvious advantages for a belligerent’s ground operations. Moreover, it permits long-lasting intelligence, surveillance, and reconnaissance (ISR) missions. It allows the use of various reconnaissance measures, such as dynamic-live drone footage, to observe the movement of the enemy and strike areas without interference or threat.

Furthermore, achieving air superiority or supremacy offers the comfort of relative safety for aircrews and increases their ability to conduct precision strikes against carefully selected targets, even in dynamic targeting operations. By contrast, in contested airspace the “time on target” window must be minimized thus restricting the aircrew’s situational awareness and ability to obtain positive identification (PID) targets. It may also require shortening the kill chain by delegating more tasks to the pilot, who will not always be supported by a Joint Terminal Attack Controller (JTAC) to provide PID and terminal guidance for the ordnance.

“Everything Feasible”

We wish to emphasize that the operational shift between air parity and air superiority affects the feasibility of certain precautions in attack, as described in Article 57 of Additional Protocol I (AP I). In other words, what would be feasible in a situation of air superiority might not be feasible in a situation of air parity. Therefore, a party to the conflict enjoying air superiority bears a heavier practical obligation to consider and implement precautionary measures compared with a party lacking air superiority.

Article 57 of AP I requires belligerents to take precautions in attack. This includes the duty to do “everything feasible” to verify the object of attack (art. 57(a)(i)) and to exercise “all feasible precautions in the choice of means and methods of attack with a view to avoiding, and in any event to minimizing, incidental loss of civilian life, injury to civilians and damage to civilian objects” (art. 57(a)(ii)). The rule establishes an obligation of conduct, not of result. The phrase “feasible” has long fueled extensive arguments about the scope of precautions in international humanitarian law (IHL). Many States interpret the duty as being limited to those precautions which are practicable or practicably possible, taking into account all the circumstances ruling at the time.

Of course, as an operational matter, obtaining air superiority does not dictate in every case the employment of technologically advanced targeting weapons and processes. When a belligerent controls the battlefield airspace, even conventional or legacy methods of aerial attacks or reconnaissance operations, such as low-attitude bombardment with unguided weapons, are sometimes called for operationally. Yet, given the relative favorability of a situation of air superiority, in terms of precautions in attack, much more is “feasible.”

Relevant Examples

In 1999, NATO operations against Serbia faced threats from surface to air missile (SAM) systems. Commanders ordered NATO aircrews not to fly below 15,000 feet altitude. The order was one of the root causes of the tragic incident in Djakovica, when NATO aircraft mistakenly bombarded a convoy of refugees fleeing Serbian ethnic cleansing. The International Tribunal for the former Yugoslavia (ICTY) ad hoc committee established to review the NATO operations heard the argument that if the NATO aircraft had been flying lower, they would have detected the civilians on the ground. While the Committee acknowledged that there was “nothing unlawful about operating at a height above Yugoslav air defences,” it did note the operational difficulty in distinguishing between military and civilian vehicles and signaled the benefit of “lower altitude scrutiny of the target at an early stage.” The committee did not recommend criminal proceedings, as it found no flagrant IHL violation by the aircrews and commanders, taking into the account the danger posed to the aircraft. The committee’s decision highlighted that the precautions taken might be limited by reasonable requirements of force protection, which are obviously more demanding in unfavorable air situations.

In the above-mentioned decision, the committee understood the circumstances of the NATO operations above Serbia. Furthermore, the committee acknowledged, at least implicitly, that NATO did not establish air supremacy during the Djakovica incident, as the crews were forced to fly beyond the range of Serbian air defense systems. The report sparked significant discussion among IHL experts pointing out that the NATO 15,000-feet policy was dangerous for civilians, although for many it was understandable from an operational perspective. Significantly, after the bombing, NATO changed its rules of engagement (ROE) to require aircrews to perform more rigorous identification of the target areas (para.68).

One may wonder how the ICTY ad hoc committee’s reasoning may have differed if at the time of the attack NATO had the highest degree of control of the air. The committee noted the aircrew and commanders displayed “recklessness in failing to take precautionary measures,” but it did not label this recklessness as criminal. Nevertheless, the committee’s reasoning is ambiguous regarding whether the threshold of criminal recklessness is somehow connected with the concept of air superiority. Our suggestion is that if NATO possessed air supremacy, and the threat of the Serbian SAM systems was not substantial, the committee would consider adopting a higher standard of feasibility with respect to the aircrews’ and commanders’ obligations to take precautions in attack.

Another example of the legal relevance of control of the air (or lack thereof) is the Ethiopia-Eritrea Claims Commission’s examination of Eritrea’s air bombardment of the Mekele airport on June 5, 1998. The Commission noted that Eritrea conducted its aerial operations in unfavorable air conditions, and that Ethiopia possessed aerial superiority (para. 108). Moreover, the Commission noted, as a mitigating factor, the inexperience of the Eritrean Air Force aircrews, acting in the conditions of both “excitement” and “confusion.” The duress and inexperience of the Eritrean Air Force, combined with unfavorable control of the air, was enough for the Commission to rule out the intentional bombardment of civilian objects.

While the Commission concluded that the Eritrean Air Force did not violate the principle of distinction, it nevertheless highlighted that the precautions employed during the strikes were insufficient. The Commission did not question the “validity of Eritrea’s argument that it had to use some inexperienced pilots and ground crew, as it did not have more than a very few experienced personnel.” Nevertheless, the scale of recklessness displayed by the air crews was sufficient to trigger Eritrea’s State responsibility. In this context, it must be emphasized that mere violation of Articles 57(a)(i) and 57(a)(ii) is not a grave breach of AP I, although a failure to exercise feasible precautions is usually (but not always) a necessary component of a violation of the principle of distinction and the proportionality rule.

Finally, in the (in)famous Goldstone Report, a UN inquiry commission referred to Israel’s superior military technology as an aggravating circumstance, on some occasions using this to support its conclusions regarding Israel’s intentional attacks against civilians and civilian objects. The UN inquiry commission highlighted the Israel Defense Forces’ (IDF) “ability to plan” as evidence of “deliberate planning and policy decisions” (para. 61). Such freedom of action is a known corollary of air supremacy.

In this regard, Professor Michael Schmitt made a crucial observation regarding precautions. He added, “a belligerent is only required to do what is feasible, and feasibility depends on the available technology.” We believe that the reasoning within the above-mentioned examples supports the conclusion that air supremacy entails a heightened legal burden with respect to feasible precautions, in the same way that technology may expand what is feasible on the battlefield. A favorable aerial situation over the target area, the freedom of maneuver of the aircrews, and the ability to deploy various means of ISR (such as long-endurance unmanned aerial systems) permit the careful execution of the weaponering stage of the targeting cycle and allow the proper identification of the target. This is the essence of the precautions principle under IHL.

By contrast, failure to achieve air supremacy impacts the feasibility of the available precautions in attack. When determining what is practicable or practically possible, the belligerent can take account of considerations such as force protection, overburdened aircrews, the possibility of erratic maneuvers to avoid air-defense fire, flying above a certain attitude, and the limitations in ISR abilities.

Practical Aspects of Precautions

States often exercise precautions in attack by applying a so-called Collateral Damage Estimation Methodology (CDEM). CDEM is a balance of science and art that produces the best judgment of potential damage to collateral concerns. The methodology assists commanders in weighing risk against military necessity and in assessing proportionality within the framework of the military decision-making process. It enables commanders to make a reasonable determination of the likely collateral damage (or incidental harm) inherent in or incident to a weapon’s employment, thus addressing IHL requirements to take feasible precautions to minimize the effects of combat on the civilian population.

Undoubtedly, the application of CDEM as a precaution in attack will be significantly easier in cases of air superiority and air supremacy. In such cases, the risk to the State’s own aircrews is relatively low, thus enabling more deliberate and careful consideration of factors potentially affecting the collateral damage estimate (CDE). Conversely, in situations of air parity or in highly contested airspace, where the risk to the State’s own aircrews and aircraft is significant and one of the risk mitigation measures is the reduction of time spent within enemy air defence zones, the application of formal CDE might be simply impossible due to time constraints and dynamics of the combat situation.

We therefore argue that in more favorable air situation, a more careful application of CDE process is feasible than in the situation of highly contested airspace. This is particularly the case for deliberate targeting in a favorable air situation. In such circumstances, a thorough CDE analysis would be significantly more feasible than during dynamic targeting, combat engagements, or in air operations conducted in highly contested airspace. In each of these cases, there are likely to be time constraints directly linked to the factor of risk to the State’s own aircrews. Put simply, the more favorable the air situation, the more feasible formal CDE processes become.

Moreover, in a full-scale conventional international armed conflict with a peer adversary, the quantity of ordnance needed to service targets may be significantly higher than in an asymmetric conflict against a technically inferior adversary without noteworthy air defence capabilities. With hundreds of air-delivered munitions employed daily, precision-guided munition (PGM) stocks could be depleted rapidly. From this perspective, the feasibility of both the formal CDE process and the use of PGMs as precautions in attack may be questionable.


Feasibility is not a constant parameter. The feasibility of precautions in attack may be considered differently for each of the belligerents, depending on factors such as their technological capabilities, the availability of PGMs, and the ability to establish a favorable air situation. Where a belligerent has achieved air superiority, we suggest that a higher standard of diligence is expected from that belligerent regarding precautions in attack. In such circumstances, feasible precautions might include: a greater use of ISR or other verification tactics (such as flying at low attitudes and with limited airspeed) to enhance the proper verification of the objective and the risks of civilian harm, application of formal CDE process or greater ration of PGMs in the overall quantity of air-delivered munitions.


Mateusz Piątkowski is an Assistant Professor in the Faculty of Law and Administration at the University of Łódź, Poland.

Ltn. Cmdr Wiesław Goździewicz is CDR/OF-4 (ret.) of Polish Navy.





Photo credit: Staff Sgt. Colin Hollowell