Warfare Across Domains: Aerial Warfare

The death birds wheel East
To their lairs again
Leaving iron eggs
In the streets of Spain.
With wings like black cubes
Against the far dawn,
The stench of their passage
Remains when they’re gone.

In his poem, “Air Raids: Barcelona” Langston Hughes evokes the harrowing aftermath of the 1937 aerial assault on the city; the unnaturally darkened skies, the wailing sirens, the innocents killed, and the bodies lying in wait under the rubble.1‘Langston Hughes On Barcelona’ (Iberianature, 2010) <https://iberianature.com/barcelona/2010/05/26/langston-hughes-on-barcelona/#more-1618> accessed 21 June 2022. In wars today, bombardment from the air is seen as part and parcel of warfare which now seeks to reach new heights with the advent of killer robots and autonomous weapons. However, it was not always so, and when it started, aerial warfare was seen as something to be prohibited, until that is, States saw the military advantages of its use. This article explores the evolution of aerial warfare, the laws of war applicable, recent military technological advancements, and what the future of war from the sky looks like.

The Evolution of Aerial Warfare

In 1783, the citizens of Versailles along with the royal family held their breaths as a duck, a sheep, and a rooster became passengers to determine whether the latest invention of the Montgolfier brothers, a hot air balloon, was to be a success.2The First Hot Air Balloon’ (Palace of Versailles) <https://en.chateauversailles.fr/discover/history/key-dates/first-hot-air-balloon-flight> accessed 21 June 2022. Lo and behold, it was! The first ever successful aerostatic flight had been achieved and consequently, a whole new realm of aerial warfare strategies was unlocked.3Ibid. In the following few decades, the French, the British and the Americans used balloons for reconnaissance and for the first time during the Franco-Prussian war in 1870, a belligerent operation using a hot air balloon was conducted.4Francisco Javier Guisández Gómez, ‘The Law Of Air Warfare’ (ICRC, 1998) <https://www.icrc.org/en/doc/resources/documents/article/other/57jpcl.htm> accessed 21 June 2022. However, following the 1903 Wright brother’s first flight in Ohio, balloons soon faded into the background as warplanes became an ever-present, gruesome reality claiming the lives of millions since.5Ibid.

A mere eight years after the first airplane was invented in 1911, it air-bombed the Ain Zara oasis during the Italo-Turkish wars.6Mark Clapson, ‘CHAPTER 1 Introduction: A Century Of Aerial Warfare’ (JSTOR, 2019) <https://www.jstor.org/stable/j.ctvggx2r2.7> accessed 21 June 2022. However, despite being able to drop bombs and provide reconnaissance, warplanes remained “primitive machines held together by wire and twine” in 1914.7Tarek Gaid, ‘Air Power And Warfare : A Century Of Theory And History.Pdf’ (Academia.edu, 2019) <https://www.academia.edu/38671578/Air_power_and_warfare_a_century_of_theory_and_history_pdf> accessed 21 June 2022. In fact, it was not until 1918 that “large, sophisticated four engine bombers had been developed”.8ibid. The First World War witnessed an evolution of the hardware and tools required to make airpower a success. Poor navigation methods, primitive engines, unsustainable airframes, and unsophisticated bomb development made it onerous for the attacking bombers to accurately reach their targets or to carry out sustained attacks during the First World War.9ibid. However, the tide changed in the Second World War. The infamous “Blitzkrieg” which enabled Hitler to move towards the English Channel at great speed, proved that sophisticated airpower was an ever-increasing necessity for success.10ibid. The Royal Air Force’s strikes on German cities, America’s bombing in Europe even through overcast skies and the devastating firebombing air raids by America on Tokyo in March 1945 claiming the lives of 100,000 Japanese, punctuated the lethality that airpower now bore.11ibid.

The Evolution of International Law on Aerial Warfare

Unfortunately, despite the ramifications of aerial warfare, no positive law exists on it unlike land and sea warfare. However, this absence of positive law does not equate to a complete lawlessness regarding air warfare as it was, and still is, subject to certain laws.

To begin with, following the invention of hot air balloons and the 1870 Balloon bombardment, the first Hague Peace Conference took place on the 29th of July 1899, and ultimately prohibited bombardment from balloons.12HAMILTON DESAUSSURE, ‘The Laws Of Air Warfare: Are There Any?’ (JSTOR, 1971) <https://www.jstor.org/stable/40704677?seq=1> accessed 21 June 2022. At the Second Hague Peace Conference in 1907, the Russian delegation proposed the renewal of the declaration; however, the adoption of the Second Balloon Declaration was far from unanimous as nations now realized the significance of air power.13Ibid. Additionally, another provision in force for the regulation of air warfare was Article 25 of the 1907 Hague Convention which, respecting the laws of customs of war on land, provided that “The attack or bombardment, by whatever means, of towns, villages, dwellings, or buildings which are undefended is prohibited.”14‘Treaties, States Parties, And Commentaries – Hague Convention (IV) On War On Land And Its Annexed Regulations, 1907 – Regulations: Art. 25 -‘ (Ihl-databases.icrc.org) <https://ihl-databases.icrc.org/applic/ihl/ihl.nsf/ART/195-200035?OpenDocument> accessed 21 June 2022. However, “undefended cities”, in the historic sense, meant only those “in the immediate zone of ground operations which could be seized and occupied by advancing ground forces without the use of force”.15DESAUSSURE, no. 12 Thus, the article proved to be as ineffective as the Balloon Declarations. To elaborate, since all territory of a state can be understood to be ‘defended’, in some way or another by its military, thus practically there are no undefended cities except for the few which have already surrendered or been evacuated in response to the advancing forces. Consequently, Article 25 provided little to no protection from air raids. Moreover, despite being the only set of formal rules agreed upon by any states, these provisions remained largely ignored when it came to belligerent air warfare operations, both, due to their ambiguity such as the term “undefended cities” in Article 25 as well as the fondness nations across the world had developed for air power.

Attempts to codify the laws of air warfare did not stop here though. On 11th November 1920, the International Committee of the Red Cross (ICRC) asked for a specific set of rules pertaining to air warfare and three years later, following the Washington Conference of 1922’s institutionalization of a Commission of Jurists in the Hague, a draft code governing air warfare came to be.16Heinz. M Hanke, ‘The 1923 Hague Rules Of Air Warfare’ (International-review.icrc.org, 1991) <https://international-review.icrc.org/sites/default/files/S0020860400071370a.pdf> accessed 21 June 2022. These “Hague Rules of Air Warfare” included 62 articles of which perhaps the ones of most interest were those enclosed in chapter IV, called “Bombardment”.17Ibid. Several imperative rules were laid down within articles 22-26; aerial bombardment for the purpose of terrorizing the civilian population, destroying or damaging private property not of military character, or injuring non-combatants was prohibited. Additionally, air bombardment to enforce compliance with requisitions in kind or payment of monetary contributions was prohibited and was only deemed legitimate when directed at a military objective, that is to say, an object of which the destruction or injury would constitute a distinct military advantage to the belligerent.18ibid. Moreover, the bombardment of cities, towns, villages, dwellings, or buildings not in the immediate neighbourhood of the operations of land forces was prohibited. In cases where there could not be bombardment without the indiscriminate bombardment of the civilian population, the aircraft was to abstain from bombardment.19ibid. The rules further specified that there must exist a reasonable presumption that the military concentration is sufficiently important to justify such bombardment, having regard to the danger thus caused to the civilian population. Moreover, a belligerent state was liable to pay compensation for injuries to person or to property caused by the violation by any of its officers or forces of the provisions of this article.20ibid. Article 25 of the rules further specified protected objects and made it necessary for commanders to take as much care as possible to avoid bombarding places dedicated to public worship, art, science, or charitable purposes, historic monuments, hospital ships, hospitals and other places where the sick and wounded are collected, provided such buildings, objects and places are not at the time used for military purposes.21ibid. Lastly, article 26 enabled states to obtain more efficient protection for important historic monuments situated within their territory, if they are willing to refrain from the use of such monuments and a surrounding zone for military purposes, and to accept a special regime for their inspection.22ibid.

However, despite all its laudatory provisions, the 1923 Hague Rules of Air Warfare failed to become a formal set of rules as not one state chose to sign or ratify it.23ibid. Yet, despite their ostensible failure, the Rules still rendered great influence on a myriad of countries in the initial years of the Second World War. For example, the 31 points encapsulated within the “Instructions Governing Aerial Warfare” of the German Air Force, issued in 1939, closely followed the Hague Rules.24ibid. Similarly, Italy, Britain and Japan, too, drew upon the Hague Rules when engaging in aerial warfare, and Britain’s instructions to its air force were even stricter than those laid down in the 1923 Rules.25ibid. Unfortunately, though, these instructions only existed during the initial years of the war whereas the latter years saw a complete disregard of any aerial warfare rules whatsoever.26Hanke, no. 16

Present Laws on Aerial Warfare

The situation regarding laws on aerial warfare remained stagnant as late as the 1970s. However, following the failure of the 19th International Conference of the Red Cross (New Delhi, 1957), a new and successful attempt was made when Additional Protocol 1 to the Geneva Conventions was adopted in 1977.27Hanke, no. 16 Interestingly, the Protocols’ Articles 48-60 were based on the main provisions of the Hague Rules of Air Warfare. Presently, the Geneva Conventions, Additional Protocols, and customary law frame the constitution for aerial warfare.

These rules lay down four distinct principles which must be adhered to during aerial warfare: the Principle of Distinction, the Principle of Humanity, the Principle of Proportionality, and the Principle of Military Necessity. The Principle of Distinction, laid down in article 48 of Additional Protocol 1 states that “In order to ensure respect for and protection of the civilian population and civilian objects, the Parties to the conflict shall at all times distinguish between the civilian population and combatants and between civilian objects and military objectives and accordingly shall direct their operations only against military objectives.”28Travis Normand and Jessica Porch, ‘4 Basic Principles’ (The Law of Armed Conflict (LOAC)) <https://loacblog.com/loac-basics/4-basic-principles/> accessed 21 June 2022. Thus, the Principle of Distinction provides, as most commentators say, “an absolute moral immunity from direct intentional attack[s] on civilians and non-combatants”.29Gabriel Sweeney, ‘Saving Lives: The Principle Of Distinction And The Realities Of Modern War’ (Scholar.smu.edu, 2005) <https://scholar.smu.edu/cgi/viewcontent.cgi?article=2355&context=til> accessed 30 June 2022. It serves a “gatekeeper role” as it determines “target selection” and if a particular target fails to meet the criteria of the principle then they can no longer be intentionally attacked. Previously the Principle of Distinction was also observed in regards to aerial warfare when the Hague Declaration 1907 prohibited the “discharge of projectiles and explosives from balloons or other similar new methods at a time when air technology was not sufficiently advanced to permit the precise targeting of objectives to be destroyed.” And thus, ensured that non-combatants remained protected.

The second principle, that is, the Principle of Proportionality, also aims to protect non-combatants during an armed conflict and hence purports, “Loss of life and damage to property incidental to attacks must not be excessive in relation to the concrete and direct military advantage expected to be gained.”30ibid. Evidently, the Principle recognizes that “collateral damage is a part of war but it attempts to reduce that damage by requiring a balancing of the costs and benefits of a proposed attack.”31ibid. Therefore, if collateral damage is expected then the military advantage must justify it while being direct and concrete. Moreover, the military advantage anticipated from an aerial attack must be from the attack as a whole, and not from isolated or particular parts of the attack. Thus, unlike the Principle of Distinction which determines who may be attacked, the Principle of Proportionality determines how an aerial attack on lawful targets may be conducted.32ibid.

On the other hand, the third and fourth principles seek to protect combatants during an armed conflict. According to the Principle of Military Necessity “…[E]very injury done to the enemy, even though permitted by the rules, is excusable only so far as it is absolutely necessary; everything beyond that is criminal.”33ibid. And therefore, it prohibits “wounding” or torturing opponents for exacting confessions or any other “additional damages on the enemy” that do not “further the military objective.” Thus, keeping in line with the Principle of Military Necessity, according to Article 42 of the Additional Protocols 1, any pilot parachuting from an aircraft in distress “shall be given an opportunity to surrender before being made the object of attack, unless it is apparent that he is engaging in a hostile act.” Similarly, “occupants escaping from a disabled aircraft cannot be attacked in the course of their descent.”34Gomez no. 4

The last principle, “Humanity” also adds to this notion as it states, “It is prohibited to employ weapons, projectiles and materials and methods of warfare of a nature to cause superfluous injury or unnecessary suffering.”35ibid. Consequently, a number of weapons such as “poisoned weapons, including projectiles smeared with substances that inflame wounds” and “projectiles filled with broken glass” have been prohibited in aerial warfare.36‘Superfluous Injury Or Unnecessary Suffering | Weapons Law Encyclopedia’ (Weaponslaw.org, 2013) <http://www.weaponslaw.org/glossary/superfluous-injury-or-unnecessary-suffering> accessed 30 June 2022. Ultimately, shaping the form aerial warfare takes.

Drones and Killer Robots

Indeed, these rules and regulations have codified aerial warfare to a certain extent. However, technological advancements of the twenty-first century have added new dimensions and layers to airpower. To elaborate, the recent advent of drones and Lethal Autonomous Weapon Systems also known as “Killer Robots” have brought forth a whole new realm of warfare. But whether these new weapons ought to be lauded or criticized for their compliance or the lack thereof with International Humanitarian Law remains debatable.

Unmanned Air Vehicles (UAVs), or drones, are remotely controlled weapons used for two main purposes: reconnaissance made easier by their ability to hover over individuals for twenty to thirty hours and carrying out attacks by dropping small armed weapons.37Nidaa Iqbal, ‘The Principle Of Distinction And Drone Strikes’ (Research Society of International Law | RSIL, 2022) <https://rsilpak.org/2022/the-principle-of-distinction-and-drone-strikes-an-ihl-accomplishment-or-an-ihl-failure/#_ftn19> accessed 21 June 2022. Over the past few decades, the USA, in particular, has used these UAVs excessively as a part of their counter-terrorism operations against Al-Qaeda.38Jelena Pejic, ‘Extraterritorial targeting by means of armed drones: Some legal implications’ IRRC (2015), 17. The proponents of drones claim that they should be praised for protecting civilians and soldiers alike by being remotely controlled and precise with their targets. However, an intuitive read would reveal that UAVs are not as compliant of the principles of armed conflict as they are deemed to be.39Iqbal, no. 37 The lack of governmental oversight “concerning the process used to weaponize the drone” as well as a lack of evidence to support the notion that the use of drones indeed “causes fewer casualties” suggests that perhaps their compliance is but a mere illusion.40Ibid.  Furthermore, the targeting of military-aged males who are present in a strike zone by the USA as well as “personality strikes” which often end up killing innocent civilians as was done when USA was targeting Osama Bin Laden and Baitullah Mehsud, support the contention that drones are not compliant with the Principle of Distinction.41Ibid.

Similar contentions are also raised for Killer Robots. These Lethal Autonomous Weapon Systems include “Harpy, a loitering munition that searches and attacks enemy radars” and the “SRG-1, an armed robot on the border between North and South Korea.”42‘Killer Robots – Peace Organization PAX’ (Paxforpeace.nl) <https://paxforpeace.nl/what-we-do/programmes/killer-robots> accessed 21 June 2022.

Today there exist three blocs when it comes to Killer Robots; those who wish to completely ban their use, those who do not support a ban such as the US, the UK and Russia, and those who want to regulate their use without an outright ban.43Brian Stauffer, “Killer Robots: Growing Support for a Ban” (Human Rights Watch, 2020), https://www.hrw.org/news/2020/08/10/killer-robots-growing-support-ban Accessed 21 June, 2022 Since 2013, about 30 countries including Iraq, Pakistan, China, Zimbabwe, and Egypt have called for a complete ban on such autonomous weapon systems.44ibid. However, notably China has only supported the idea of banning the use of Killer robots and not their production or development which they themselves are presently involved in.45ibid. Similarly, the Non-Aligned Movement of 125 countries has since 2018 called for a “legally binding international instrument stipulating prohibitions and regulations on lethal autonomous weapons systems.”46ibid. Formal talks by state parties to the Convention on Conventional Weapons also inaugurated in 2017 regarding the use of Killer Robots.47ibid.

Evidently, Killer robots also go against the Martens Clause in accordance to which:

“In cases not covered by this Protocol or by other international agreements, civilians and combatants remain under the protection and authority of the principles of international law derived from established custom, from the principles of humanity and from the dictates of public conscience.”48Martens Clause, as stated in Additional Protocol I of 1977 to the Geneva Conventions

Yet, despite these perceptible incongruencies with IHL, the production and usage of these deadly weapons continues. Unfortunately, it seems that with “such strong opposing positions, coming to an international agreement will not be easy”.49Coley Felt, ‘Autonomous Weaponry: Are Killer Robots In Our Future? – The Henry M. Jackson School Of International Studies’ (The Henry M. Jackson School of International Studies, 2020) <https://jsis.washington.edu/news/autonomous-weaponry-are-killer-robots-in-our-future/> accessed 22 June 2022. And until an agreement is reached, the world will continue to move towards an uncertain and gloomy future.        

What Does the Future Look Like?

Lethal autonomous weapon systems, deadly unmanned air vehicles, hypersonic missiles, and self-piloting fighter jets, amongst other technological advancements, present themselves as harbingers to an apocalyptic end to civilization. An end characterized by morally depraved killing machines, lethal Roomba’s gone mad, devastating flash wars and skies swarming with killer drones, too fast for the human eye to keep track of yet loud enough to announce the coming of death.50Thomas Ricks, ‘Fighting Wars Past, Present And Future (Published 2018)’ (Nytimes.com, 2018) <https://www.nytimes.com/2018/05/25/books/review/army-of-none-paul-scharre.html> accessed 30 June 2022.

In his book “The Army of None”, Paul Scharre, whilst elaborating on a future punctuated by automated weapon systems, presents a bleak reality where life and death decisions would eventually be made by machines.51ibid. Therefore, although the “autonomy” given to killer robots brings about precision when targeting enemies and serves as a useful military strategy, unfortunately, it also brings about great moral ambiguities. To elaborate, a soldier in the field would hesitate and, most likely, not kill a five or six-year-old even if they were spies for the enemies due to the conscious realization of them being a child. On the other hand, automated systems would be devoid of such hesitance or humanity and would perceive the child as a mere target- adding new layers to the brutality of war.52ibid.

However, a morally questionable future is not all that we have to fear. Rogue soldiers, unintended escalations, nuclear explosions, and complete and utter chaos- the aforementioned technological advancements may “upend everything about human conflict and aerial warfare as we know it, including whether humans are involved or not”.53DW News (4 June 2021) <https://www.youtube.com/watch?v=TmlBkW6ANsQ&t=1876s> accessed 30 June 2022 As these weapons become increasingly dependent upon Artificial Intelligence, it is evident that a minute error, a simple miscalculation or a wrongly perceived threat would set off a chain of events that would have devastating consequences: morphing the entire world into a self-destructing warzone as drones would fill the sky, and defence missiles would be automatically launched to deal with any perceived threat- even a false one54ibid.

Therefore, although there is a great likelihood that battlefields and warzones will soon become void of any human soldiers, there is no surety that this will reduce war casualties due to the erroneous consequences AI-dependent weaponry can have. Presently, the world seems to be becoming increasingly volatile with every new automated machine and the threat of a horrific aerial war ever more solemn.


Throughout the centuries, aerial warfare has developed into a formidable force. Its evolution dates back to 1783 with the advent of hot air balloons and, after numerous trials and errors, morphed into unmanned air vehicles in the twenty-first-century that can observe for extended periods of time as well as render significant damage without the need of any soldiers accompanying them into war-zones. However, this development of aerial weapons has not proceeded unregulated by the international community, as IHL has recurrently attempted to codify laws regarding aerial warfare, aiming to strike a balance between military necessity and humanitarian concerns. However, despite the existence of laws on the use of weapons, particularly the four principles of the law of armed conflict, the invention of autonomous weapon systems, especially killer robots and unmanned drone vehicles, nudge us towards an uncertain future. Unquestionably, there exists an imperative need to formulate and ratify laws governing aerial warfare and the existence of these newer weapons if the world is to become a safer place.


The opinions expressed in the articles on the Diplomacy, Law & Policy (DLP) Forum are those of the authors. They do not purport to reflect the opinions or views of the DLP Forum, its editorial team, or its affiliated organizations. Moreover, the articles are based upon information the authors consider reliable, but neither the DLP Forum nor its affiliates warrant its completeness or accuracy, and it should not be relied upon as such.

The DLP Forum hereby disclaims any and all liability to any party for any direct, indirect, implied, punitive, special, incidental or other consequential damages arising directly or indirectly from any use of its content, which is provided as is, and without warranties.

The articles may contain links to other websites or content belonging to or originating from third parties or links to websites and features in banners or other advertising. Such external links are not investigated, monitored, or checked for accuracy, adequacy, validity, reliability, availability or completeness by us and we do not warrant, endorse, guarantee, or assume responsibility for the accuracy or reliability of this information.

Aimun Munir

Aimun Munir is a BA-LLB student at the Lahore University of Management Sciences (LUMS).