Weapons of mass destruction

The central ethical question is not simply whether these weapons can defeat an enemy. It is whether achieving a military aim can justify the suffering inflicted on people who are not fighting, future generations and the environment.

Chemical, biological and nuclear weapons

Chemical weapons use toxic chemicals to poison or injure people. Exposure can occur through breathing them in or through contact with the skin or eyes. Depending on the chemical, victims may suffer burns, blindness, breathing difficulties or death. Survivors can experience lasting illness.

Iraq used mustard gas and nerve agents during the Iran–Iraq War in the 1980s. The chemical attack on Halabja in 1988 killed around 5,000 civilians. This illustrates why chemical weapons raise questions about protecting innocent life, not just military effectiveness.

Biological weapons use disease-causing organisms, such as bacteria or viruses, or toxins produced by living organisms. They can cause severe illness and death. Some can produce outbreaks that spread beyond the original target and overwhelm healthcare services, although not every biological agent spreads between people. In the United States in 2001, letters containing anthrax spores killed five people and spread fear.

Nuclear weapons release enormous energy through nuclear reactions. Their blast and heat can destroy buildings and kill or burn people, while radiation can cause further illness and long-term harm. The United States used atomic bombs against Hiroshima and Nagasaki in Japan in 1945. Nuclear weapons belong to the same broad category of WMD, although debates about nuclear deterrence also have distinctive features.

Across these weapons, the harm is not limited to immediate deaths. Attacks can damage hospitals, water supplies and other essential services, force people from their homes and cause psychological trauma. The exact consequences depend on the weapon: poisoning, infectious disease and radiation are different dangers, not effects shared by every WMD.

Why protecting civilians matters

Two important principles for judging warfare are discrimination and proportionality. Discrimination means distinguishing combatants from civilians and protecting those who are not fighting. Proportionality means that military action must not cause excessive harm in relation to its legitimate aim.

WMD are especially difficult to reconcile with these principles. Poison or disease may harm people outside the target area, while large-scale destruction can kill civilians alongside soldiers. Even a legitimate aim, such as defending a country, does not make every method of achieving it acceptable.

International agreements reflect these concerns. The 1925 Geneva Protocol prohibited the use of chemical and biological weapons in war. The 1972 Biological Weapons Convention went further by prohibiting their development, production and stockpiling, among other activities, and requiring their destruction. The Chemical Weapons Convention, adopted in 1993 and entering into force in 1997, prohibits chemical weapons, including their development, production, stockpiling and use, and requires their destruction.

These agreements should not be confused with the 1949 Geneva Conventions, which protect people affected by armed conflict. Nor should the chemical and biological weapons bans be treated as a blanket ban on all nuclear weapons.

Christian arguments against their use

Many Christians oppose WMD because of the sanctity of life: human life comes from God and is sacred. The commandment ‘You shall not murder’ (Exodus 20:13) supports opposition to weapons that kill innocent people. The argument is that civilians do not lose their value as human beings because they live in an enemy country.

Jesus also taught, ‘Love your enemies’ (Matthew 5:44). Christians can apply this by arguing that causing indiscriminate suffering is incompatible with treating enemies with love. Christian pacifists, who reject war and violence, therefore oppose WMD as well as other weapons.

Christians who accept just war reasoning can also reject WMD. They may believe that armed defence is sometimes justified but that civilians must be protected and force must be proportionate. Supporting a defensive war does not require accepting chemical, biological or nuclear attacks.

Contrasting religious and non-religious judgements

Some Christians distinguish possession from use. They argue that possessing a powerful weapon may deter aggression and protect lives without it ever being used. Jesus’ teaching ‘Blessed are the peacemakers’ (Matthew 5:9) can support their aim of preventing war. This argument is most commonly associated with nuclear weapons; it does not remove the prohibitions on chemical and biological weapons.

Other Christians challenge this reasoning. If deterrence depends on threatening an act that would be morally wrong, they ask whether that threat can genuinely promote peace. Accidents, miscalculation and escalating fear also weaken the claim that possession guarantees safety.

Muslims can oppose WMD because life is sacred to God. The Qur’an teaches, ‘Take not life that God has made sacred’ (6:151). It also permits fighting against attackers while warning, ‘Do not overstep the limits’ (2:190). Applied to WMD, these teachings support the argument that even legitimate defence must have limits and must not justify indiscriminate killing.

A humanist may reach a similar conclusion without belief in God. Humanists use reason, evidence and concern for human wellbeing. Civilian deaths, lasting illness and environmental damage provide strong reasons to reject WMD. Countries with fewer healthcare and emergency resources may also suffer more severely, raising questions of fairness.

A contrasting, consequence-based argument asks whether using a weapon could prevent even greater suffering. For example, some defenders of the 1945 atomic bombings argue that they shortened the war and avoided further deaths. This is a claim about what might otherwise have happened, not proof that mass destruction is justified. Critics question whether the claimed benefit outweighs civilian suffering or whether less destructive alternatives were available.

Reaching a justified judgement

Possession also carries risks before a weapon is used. Secret programmes create mistrust, materials may be stolen or misused, and safe storage and destruction require specialist equipment and funding. Chemical and biological weapons can threaten security rather than simply provide it.

A reasoned conclusion should identify which consideration is most important. Someone might accept the responsibility to defend a population but conclude that indiscriminate harm makes WMD unacceptable methods of defence. Alternatively, someone might support nuclear possession as a deterrent while rejecting actual use and opposing chemical and biological weapons.

The strongest judgement addresses the opposing case: preventing aggression is a serious aim, but it must be weighed against the reliability of deterrence, the protection of civilians and the lasting consequences of an attack.