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Engineering in Conflict: An Engineer’s Ethical Responsibility based on Just War Theory

Military engineering has existed for as long as wars and conflicts have, which unfortunately has been a constant in human history; it has long been a needed profession that demands substantial time, money, and energy from a population. Even in ancient times, societies invested enormous efforts into military engineering. One of the Seven Wonders of the World, the Great Wall of China, was “built from the 3rd century BC to the 17th century AD” to protect China from northern raids and conflicts (UNESCO, n.d.). In 2023, the Aerospace and Defense industry’s workforce had “2.211 million employees, representing 1.4 percent of the nation’s total employment base,” according to the Aerospace Industries Association (AIA, 2024). A completely peaceful world is an ideal situation that humanity should continue to strive towards, but that world is unfortunately unlikely to emerge soon. Until society can attain that perfect world, everything must be done to keep wars and conflicts as humane and ethical as possible. Engineers are not typically thought of as major components in wars, as they are physically separated from the battlefield; however, engineers serve as pivotal figures in warfare, as their technological advancements continuously reshape military conflicts and therefore, human history.

Just War Theory is an ever-evolving philosophical framework for evaluating the morality of conflicts. “Originating with the bishop of Hippo, St. Augustine, it now manifests itself as the basis of international humanitarian law” (Elkins, 2024). It provides a structured yet flexible approach to determining when the conduct of a war is morally justifiable. While traditionally applied to political and military leaders, its principles can also be interpreted to guide engineers, whose work directly influences the conduct of war. It comprises three main principles: Jus Ad Bellum, Jus in Bello, and Jus Post Bellum. The Right to War, Jus Ad Bellum, states that a group entering a war must do so for a just reason. It is largely believed that this means that there are no alternative options other than a physical conflict and that human lives are being risked or threatened. Although this point is rather political, engineers still have an ethical responsibility to consider how their work may be used and whether it aligns with their moral beliefs. In the context of military technology, this means engineers should try to avoid contributing to conflicts or weapons they believe are unjust. The second point is Jus in Bello, Justice in War, and it is the most relevant to engineers and will be discussed in depth shortly. The final principle of Just War Theory is Jus Post Bellum, which means Justice After War, involves treating survivors and veterans from both sides in a dignified manner. This point is quite important to engineers, as after conflicts, many people from both sides of the conflict are in need of medical treatment and resources quickly. Engineers and others have an immense responsibility to allocate these resources and must do so in a fair and equitable way, while also being as efficient as possible.

Justice in War, “Jus in bello regulates the conduct of parties engaged in an armed conflict” but can be further defined with three sub-points: Discrimination, Proportional Force, and Military Necessity (ICRC, 2015). Military leaders and engineers would consider these points in distinct but complementary ways. Discrimination, to military leaders, means the attack must distinguish between the threat and civilians, or even between a target and other soldiers. Proportional Force directs that the attack would have to be reasonable compared to the opposition's strike or threat. Finally, Military Necessity states the strike must provide a significant gain in the conflict instead of simply causing needless violence. These points can also be compared to the weapons produced by engineers. A weapon must be accurate enough to only harm its intended target and cause no other damage. A weapon must be a reasonable solution to the conflict and not be overly forceful. Lastly, a weapon must serve the purpose of the war and never reach the level of cruelty. While this final ethical boundary is theoretically the most rigid, history is unfortunately marked by instances where engineers have bypassed it, culminating in some of the most horrific and devastating technological developments. The United States Congress’s current statement about these principles in terms of weapons is that, “Jus in bello limits the weapons states can use during armed conflict. It prohibits two general categories of weapons—those that by nature cause superfluous injury or are inherently indiscriminate—and certain specific weapons, such as poisonous weapons and gases, chemical weapons, and biological weapons” (Congressional Research Service, 2022). History can be a helpful aid to further illustrate these principles and the point of view of the United States.

The World Wars occurred during a time of mass innovations and manufacturing. In World War I, many different technologies and weapons were newly created or heavily advanced for the war efforts. Two of the most significant innovations were chemical weapons and airplanes; neither had been employed on such a large scale in any prior conflicts, yet both had huge impacts on WWI. By World War II, plane technology had rapidly improved, and both sides of the conflict heavily utilized the skies in the war, but chemical warfare had been banned. Why was one weapon deemed ethical when the other was not? Is it because Germany invented and used chemical weapons on a large scale first? Or is it because a plane represents a tangible, visible adversary, whereas chemical warfare poisons the soldier's surroundings?

While the world's perception of the matter definitely played a large role, the rules of Just War Theory explain why these two weapons had different ethical connotations. Chemical weapons are fundamentally unethical inventions, whereas planes had the potential to be an ethical form of fighting, yet fell short in WWI. In WWI, both planes and chemical weapons were terribly indiscriminate. Planes were forced to higher altitudes than predicted during attacks due to ground fire and defenses, and had little to no form of aiming, as many projectiles were simply tossed out of the cockpit by the pilot, especially in earlier battles. These darts, called fletchettes, were roughly 5 inches long, weighed a pound and “were dropped from aeroplanes or airships in great numbers, each canister holding between twenty and 250 darts” creating a terrifying situation for ground soldiers (Australian War Memorial, n.d.). However, planes held the promise of becoming more accurate and therefore less discriminatory. Chemical weapons, on the other hand, are possibly the most notorious example of indiscriminate weapons. They harmed soldiers, medical staff, and civilians alike. Additionally, they were heavily influenced by winds, creating a huge risk to nearby towns or even the Germans’ own forces. Certain chemicals, such as the chlorine from Chlorine Gas, would seep into the soil and water sources, remaining for up to months, affecting the resources of nearby civilians. The Rhine River creates a long stretch of border between France and Germany, additionally it was used by many as a source of drinking water during WWI. Leverkusen, Germany, was one of these areas and found a disturbing increase in chemicals in their drinking water. “Chlorine concentrations jumped from 31.9 milligrams per liter of water in September 1914 to 61 milligrams per liter by January 1917” (Johnson, 2011, p. 12). Chemical weapons also had immediate, devastating impacts on the environment. On April 30th, 1916, an officer reported “the grass and crops over which the gas-stream passed had been bleached and more or less destroyed. . . It is reported that several cows and pigs and a considerable number of rats were killed” (Thomas, 1985). This momentary struggle for position destroyed the entire ecosystem it took place in. In short, chemical weapons are nearly impossible to have full control over and will inevitably harm more than just the desired target, making them inherently highly indiscriminate.

Continuing with the Jus in Bello principle from Just War Theory, a weapon should cause damage proportional to that which the enemy is inflicting as defined by Proportional Force. During WWI, planes were far from creating a huge impact. The idea of planes entirely bypassing ground forces and targeting civilians was a big concern at the time, but this proved harder than expected, and planes had very limited power compared to what they would have in WWII. Planes were originally used for scouting missions or reconnaissance by all major forces of the war, like “at the battles of Mons, the Marne, and Tannenberg. In 1914, air power, with varying degrees of success, provided intelligence via reconnaissance and observation, which provided situational awareness to ground commanders” (Mahoney & Pugh, 2026). In acts of offense, pilots would drop bricks, fletchettes, or bombs from the plane, but the first forward facing machine gun was only placed on a plane in 1915, meaning the technology was still in a formative phase during the war. By WWII, this military technology had been thoroughly developed and not all attacks with planes since WWI have been proportionate and discriminatory. How a weapon is used still holds a lot of weight in moral dilemmas but to an engineer the fact that a weapon is inherently designed to be used ethically is what is most essential. Chemical weapons, on the other hand, caused a great deal of harm; The poison would often take several days to kill its victims, leaving the soldiers' final few days to be painful and vile. Pictures and accounts of these attacks are sickening and, truthfully, are hard to describe. The mixture of gases that the Germans used to cause more suffering was plainly a harsh way to die, and the public at the time felt similarly. Chemical warfare was past ordinary war tactics, and it was deemed to be a force completely disproportionate to the suffering caused by a bullet.

Finally, a weapon should have military necessity, and it is seen again that chemical weapons violate this rule, while planes do not. Aerial reconnaissance had quickly become essential to both militaries for information. As previously mentioned, planes acted as scouts and brought information about the enemy's troops and the battle back to military leaders. This information became highly necessary, and adding weapons to the planes did not change the importance of the information. On the other hand, chemical weapons proved not to hold much military significance at all, as “chemical warfare caused less than 1% of the total deaths in this war [but] the ‘psy-war’ or fear factor was formidable” (Patton, n.d.). Beyond their cruelty, chemical weapons proved operationally ineffective due to a range of tactical liabilities, such as unpredictable wind dispersion and the creation of uninhabitable terrain. By deliberately compounding toxic mixtures to create additional agony, these designs bypassed military utility and descended into sheer cruelty, directly violating the core tenets of Jus in Bello. In the end, they caused profound suffering for minimal strategic gain. While planes can be employed within ethical boundaries, chemical weapons fail every measure of Just War Theory.

Prior to WWI and the thousands of lives taken by chemical weapons, a legal attempt to outright ban chemicals had already happened. The Hague Conventions of 1899 and 1907 specifically stated that, “The Contracting Powers agree to abstain from the use of projectiles the sole object of which is the diffusion of asphyxiating or deleterious gases” (International Committee of the Red Cross, 1899). Quickly, the German engineers found a loophole in this, as their chemical weapons were in canisters buried in the ground, not carried in projectiles, making chemical weapons perfectly legal again. This was a legal oversight that was quickly taken advantage of by engineers, allowing warfare to be more sadistic than it already was. After WWI the Geneva Protocol marked another legal attempt to ban the use of chemical and biological warfare. 38 countries signed it, including the United States and Germany, and it was a massive step toward a more peaceful world. However, many countries were still scared of the threat of chemical weapons being used on them, so many agreed to a clause that they would not be the first to use them in conflict, but that they would do so without hesitation if chemical weapons were used on their forces first. This meant that most World Super Powers, including the United States, continued to research, engineer, mass-produce, and store chemical weapons, simply waiting to use them. Thus, the Geneva Protocol was ineffective at eradicating chemical weapons; while it deterred countries, it definitely did not stop them. Finally, the Chemical Warfare Convention took place in 1993, and it currently has 193 nations’ support. This was an outright ban on the development, production, transfer, stockpiling, or use of chemical weapons. During this convention, the Organisation for the Prohibition of Chemical Weapons (OPCW) was created, which had the ability to investigate and enforce the rules set in place. This was one of the biggest steps towards permanent peace in history as the organisation was created and still acts to “permanently and verifiably eliminate chemical weapons” (OPCW, n.d.).

It took over 90 years of legal battles and countless lives ruined to ban chemical weapons in warfare, but legal action is still not a guaranteed solution. Even after the Chemical Warfare Convention and the vast new legal frameworks it put in place in 1993, there have still been 52 chemical attacks carried out by various countries since, causing the deaths of over half a million people and injuring thousands more. This includes countries or groups that are not a part of these legalities, parties that have operated in secret, and countries in the agreement that have blurred the lines of chemical warfare. For example, Agent Orange was used as a herbicide by the United States in the Vietnam War. It was designed to destroy the dense forest that US forces were struggling to combat but still proved harmful to civilians and soldiers nevertheless. Multiple terrorist attacks and assassinations have also been carried out with chemical weapons, such as ISIS in 2006 to 2007 where chlorine gas was used acting as a pulmonary agent and harming 115 civilians during a spree of 15 different attacks or the assassination of Alexander Perepilichny, a former Russian banker whistleblower carried out with Gelsemium elegans o Heartbreak Grass. These are just a few of the devastating accounts of chemical weapons. Once any technology is released to the world, it is impossible to recontain it; with weapons, this has a huge moral implication. Legal action typically lags behind new technologies because of their ever-evolving nature, therefore engineers in defense roles must be cognizant of this power they possess.

Engineers are so physically distant from battlefields that their moral decisions may appear diluted and insignificant. First, a country's leader authorizes a war, military leaders must formulate a plan and then order soldiers to execute it, all before the engineer's weapon would be used. However, engineers are the ones who decide what is inevitably placed in the hands of the soldiers. Ensuring the creation of a discriminatory, reasonably forceful, and necessary weapon is an engineer's ethical responsibility. Political leaders, military leaders, and soldiers all must exercise the same moral character, as it is still possible to violate Just War Theory even if the strike is carried out with an ethical weapon. Conversely, no amount of just cause can condone the use of an unethical weapon. Once an idea has been released into the world, it is impossible for it to completely go extinct; legal action and public persuasion are honorable and impactful methods to fix these mistakes, but it is an engineer's responsibility to ensure these mistakes never take place to begin with.

Many other ethical standards could be used to analyze an engineer's ethical responsibility in conflict, but it is impossible to elaborate on every point in this vast discussion. Nevertheless, these are conversations that must be had. There are many other weapons that the world has deemed unethical, and others are still being argued, just as there are many viewpoints on war and the morality of every conflict. There is no clear cut rulebook to the ethics of a conflict, but engineering ethics in wartime should be an explicit part of education and professional practice rather than a topic avoided because of political sensitivity and heavy subject matter. Students and professionals need structured and open conversations about these dilemmas because no one can resolve them alone.

Conflicts continue to appear in the news seemingly daily. As of June 2026, there are 28 active armed conflicts worldwide (Council on Foreign Relations, 2026). Humanity must keep striving for peace and protecting human lives, but military technologies will continue to advance as humanity does; engineers must therefore accept responsibility for ensuring that the tools they create uphold ethical standards and protect both soldiers and civilians from unethical warfare.

References

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