Are Drones Legal in Armed Conflicts?

Edmarverson A. Santos
Jun 17
16 min read

Updated: Jun 24

I. Introduction: Legality of Drone Warfare in Modern Conflicts

Are drones legal in armed conflicts? This pressing question lies at the intersection of emerging military technologies and international humanitarian law. Since their widespread deployment after the 9/11 attacks, armed drones have transformed the modern battlefield. Governments praise their precision and strategic effectiveness, while human rights groups warn of potential legal and ethical violations. As unmanned aerial vehicles (UAVs) become central to military operations across conflict zones—from Yemen to Pakistan—their compliance with the laws of war is under intense scrutiny.

Drones introduce unique legal challenges. Unlike conventional weapons, they allow states to strike targets remotely, often in sovereign territories without active war declarations. This has triggered debates over state sovereignty, targeted killings, and the erosion of the combatant-civilian distinction. Moreover, the reliance on real-time surveillance and data analysis raises concerns about accountability and the dehumanization of warfare.

To determine if the use of drones complies with international law, it is necessary to examine their application under the four core principles of the Law of Armed Conflict (LOAC): distinction, proportionality, humanity, and military necessity. These principles, codified in the Geneva Conventions and Additional Protocols, govern the conduct of hostilities and the protection of civilians during war. Violations of these principles may constitute serious breaches of international law, including war crimes.

This article investigates these legal dimensions, focusing on how drones are used, the ethical implications of remote warfare, and specific state practices—particularly the case of U.S. drone strikes in Yemen. While technology offers unprecedented accuracy, legal compliance depends not on the weapon itself but on how it is deployed. Through legal analysis and field case studies, this study explores when drone strikes may be deemed lawful and where they fail to meet international standards.

II. Legal Frameworks Governing the Use of Drones

International humanitarian law (IHL), also referred to as the Law of Armed Conflict (LOAC), governs the conduct of hostilities during times of war. It seeks to balance military necessity with humanitarian concerns by protecting persons who are not—or are no longer—taking part in the fighting. When addressing the question “Are drones legal in armed conflicts?”, understanding the applicable legal framework is crucial.

1. Sources of Law

The primary sources of IHL include:

The four Geneva Conventions of 1949.
Their Additional Protocols of 1977 and 2005.
Customary international law.
Case law from international tribunals (e.g., Prosecutor v. Tadić at the ICTY).
The UN Charter, especially Article 2(4) on the prohibition of the use of force and Article 51 on self-defense.

According to the ICTY in the Tadić case, an “armed conflict exists whenever there is a resort to armed force between States or protracted armed violence between governmental authorities and organized armed groups.” This definition applies to both international and non-international armed conflicts and broadens the context in which drone operations may fall under IHL.

2. Classification of Conflict

Drones may be deployed in both:

International armed conflicts (IACs), where hostilities occur between states.
Non-international armed conflicts (NIACs), involving conflicts between states and non-state actors or between such groups within a state.

The classification is not trivial. The legal rules applicable may vary. For example, while all Geneva Conventions apply to IACs, only Common Article 3 and Additional Protocol II apply to NIACs. Drones used outside clearly defined conflict zones raise further legal ambiguity, especially when operated without the consent of the host state.

3. The UN Charter and Use of Force

Article 2(4) of the UN Charter prohibits the threat or use of force against the territorial integrity or political independence of any state. Article 51 permits self-defense in response to an armed attack. States justify drone strikes on foreign soil by invoking the right to self-defense against non-state actors (e.g., al-Qaeda or ISIS). However, such justification requires that the host state is either unwilling or unable to prevent the threat, a standard that remains legally and politically controversial.

In Yemen, for example, the U.S. has conducted drone strikes based on a broad interpretation of self-defense, yet legal scholars argue that some operations lacked the host state’s consent and thus breached Article 2(4).

4. Weapons Review Obligations

Article 36 of Additional Protocol I obligates states to determine whether new weapons or methods of warfare comply with international law. This includes assessing drones for compliance with IHL. The review must evaluate:

Capacity to distinguish between combatants and civilians.
Likelihood of causing unnecessary suffering.
Compliance with principles of proportionality and military necessity.

Despite their advanced technology, drones are not inherently lawful or unlawful under IHL. Their legality depends on how and where they are used.

5. Challenges with Accountability and Transparency

The remote nature of drone warfare complicates traditional accountability mechanisms. Operators may be geographically and politically detached from the battlefield, and targeting decisions are often classified. This lack of transparency undermines legal oversight and the ability to assess compliance with IHL.

Some states also employ “kill lists” and conduct “signature strikes,” targeting individuals based on behavioral patterns rather than confirmed identity. These methods raise serious legal questions regarding due process, sovereignty, and distinction.

In conclusion, while drones can be operated within the bounds of international law, doing so requires strict adherence to legal norms governing armed conflict. The growing reliance on remote strikes calls for robust legal reviews, greater transparency, and international cooperation to ensure these weapons remain under lawful and ethical control.

III. Core IHL Principles Applied to Drone Warfare

The legality of drones in armed conflicts is contingent not on the weapons themselves but on how they are used. International Humanitarian Law (IHL) provides four foundational principles to evaluate the conduct of hostilities: distinction, proportionality, humanity, and military necessity. Each plays a central role in assessing whether drone strikes conform to the rules of war.

1. Distinction

The principle of distinction obliges parties to a conflict to differentiate at all times between combatants and civilians, and between military objectives and civilian objects. Codified in Article 48 and 52(2) of Additional Protocol I to the Geneva Conventions, this rule prohibits attacks that are not directed at legitimate military targets.

Drones, with their long surveillance capacity and real-time intelligence, have the potential to enhance compliance with this principle. They can monitor targets for hours or days, allowing operators to verify patterns of life and reduce uncertainty. However, challenges persist in asymmetric conflicts where combatants do not wear uniforms and often embed themselves within civilian populations.

Two targeting methods are often used:

Personalized (direct) strikes, aimed at specifically identified individuals.
Signature strikes, based on behavioral patterns deemed suspicious, without confirmed identity.

Signature strikes pose greater legal risks. They can result in civilians being wrongly targeted due to mistaken interpretation of behavior. According to the ICRC, membership in an armed group is not sufficient to lose protection; only those who assume a continuous combat function may be lawfully targeted.

The accuracy of drone sensors and reliance on intelligence data can support distinction, but when data is flawed or misinterpreted, violations occur. For example, targeting a tribal council (jirga) in Pakistan led to numerous civilian deaths, even though the strike was believed to hit militants.

2. Proportionality

Proportionality prohibits attacks that may cause incidental civilian harm excessive in relation to the anticipated military advantage. This principle, outlined in Article 51(5)(b) of Additional Protocol I, does not forbid all civilian casualties but requires that harm to civilians is not disproportionate to the military gain.

Drones are designed to reduce collateral damage through precision strikes. However, their use has resulted in controversial incidents. One well-documented case involved a drone targeting a meeting in Pakistan—believed to host militants—which turned out to be a civilian gathering. Such cases raise doubts about how proportionality assessments are made.

Another layer of concern is psychological harm. Constant drone presence can cause widespread fear, disrupting daily life and inducing trauma. The ICRC recognizes this as a possible breach of proportionality, especially when psychological effects are systematic and not incidental.

3. Humanity

The principle of humanity, or the prohibition of unnecessary suffering, is codified in Article 35(2) of Additional Protocol I and the 1868 St. Petersburg Declaration. It forbids methods or means of warfare that cause superfluous injury or harm not justified by military necessity.

Drones typically use Hellfire missiles, which are not inherently illegal and do not cause suffering beyond standard expectations of armed conflict. Their high precision capability may, in fact, contribute to minimizing unnecessary harm—provided strikes are properly planned and executed.

However, ethical critiques argue that drone warfare fosters a form of psychological detachment. Operators may not directly witness the consequences of their actions, raising questions about the erosion of human empathy in targeting. At the same time, drone operators often experience high levels of PTSD due to prolonged surveillance and intimate observation of targets before striking, revealing a paradox between technical distance and emotional proximity.

4. Military Necessity

Military necessity justifies the use of force only when it is intended to achieve a legitimate military objective. This principle permits destruction of property or targeting of individuals when required by the exigencies of war and constrained by IHL.

Drone strikes must meet this threshold. The attack must target combatants or objects making an effective contribution to military action. In practice, this means that every drone operation should be evaluated for its concrete military gain relative to the associated risks.

Drones excel in selective targeting, which aligns well with military necessity. Yet excessive reliance on them may lower the political threshold for engaging in hostilities. As the risks to military personnel decrease, states may resort to force more quickly, potentially stretching the interpretation of what constitutes "necessity."

Summary Table: Compliance of Drones with IHL Principles

Principle	Legal Basis	Drone Compliance	Key Challenges
Distinction	AP I Art. 48, 52(2), 57	High surveillance accuracy supports distinction	Mistakes in intelligence; risk with signature strikes
Proportionality	AP I Art. 51(5)(b)	Precision reduces collateral damage	Civilian deaths from flawed targeting; psychological trauma
Humanity	AP I Art. 35(2); St. Petersburg Declaration	Drones don’t use banned weapons	Ethical debate over dehumanization; psychological stress
Military Necessity	AP I Art. 52(2); Protocol II Art. 17	Targeted strikes serve clear tactical goals	Overuse risks undermining proportionality and distinction

Taken together, these principles show that drones can be lawful weapons under IHL—provided states rigorously assess and enforce compliance in each individual operation. Legal violations often arise not from the technology but from how and why it is employed.

IV. Ethical Concerns: Dehumanization and Targeting Practices

The expanded use of drones in armed conflicts has provoked intense ethical debate, particularly regarding the psychological and moral dimensions of remote warfare. Even when drone operations satisfy the formal requirements of international humanitarian law, ethical concerns persist around how such strikes are conducted, who is targeted, and the broader effects on both combatants and civilians.

1. Individualization vs. Dehumanization

Drone warfare paradoxically fosters both individualization and dehumanization. On the one hand, drones enable precision attacks on specific individuals, sometimes after prolonged surveillance and intelligence gathering. These personalized strikes—also called direct strikes—target named individuals considered high-value military threats.

On the other hand, this apparent precision may mask a process of ethical detachment. Targets become digital images observed from thousands of kilometers away. The physical and emotional distance between operator and target raises concerns about the erosion of empathy and accountability. In the words of some scholars, drones turn human beings into mere “signatures,” patterns of life reduced to behavioral algorithms.

Drone operators report high rates of psychological stress and post-traumatic stress disorder (PTSD), often because they observe their targets for days and even watch the aftermath of the strike. Despite being geographically removed, they may feel emotionally entangled with the individuals they kill. This cognitive dissonance highlights the complex human cost of “clean” warfare.

2. Signature Strikes and the Risk of Misidentification

One of the most controversial targeting practices in drone warfare is the use of signature strikes. Unlike direct strikes, which require specific intelligence confirming a person’s identity, signature strikes are based on behavioral indicators deemed suspicious—such as frequenting known militant areas or associating with identified operatives.

These criteria are inherently ambiguous. The reliance on behavior, rather than confirmation of combatant status, increases the risk of wrongful targeting. Civilians may be killed simply because their daily routines align with a behavioral profile generated by algorithms and surveillance data.

Legal scholars and human rights advocates argue that signature strikes risk violating the principles of distinction and proportionality, even if they appear lawful in internal military assessments. The opacity of these strikes—often conducted without public disclosure of the evidence used—compounds ethical concerns.

3. Follow-up Strikes and Attacks on First Responders

Another deeply troubling practice involves follow-up strikes, also known as “double taps.” These are secondary strikes launched at the scene of an initial drone attack, targeting individuals who arrive to help the wounded or attend funerals. Such strikes raise significant ethical and legal issues.

International humanitarian law prohibits attacks on persons who are hors de combat, including the wounded, medical personnel, and civilians offering assistance. Striking first responders may amount to a war crime and undermines the protection of humanitarian action.

Beyond legal dimensions, follow-up strikes fuel local resentment, radicalization, and loss of trust in the humanitarian principles of war. They also discourage civilian populations from assisting victims, deepening the humanitarian toll.

4. Ethical Critiques: Riskless Killing and Asymmetry of Power

Drones allow military personnel to conduct lethal operations without being physically present in the conflict zone. This creates what some ethicists call a form of riskless killing, where one party assumes no immediate danger while the other is fully exposed.

Critics argue that this violates the moral symmetry expected in warfare, where combatants share the burden of risk. The power imbalance is further exacerbated by the invisibility of drone operators and the impossibility for those targeted to defend themselves or surrender.

Moreover, some scholars contend that this detachment leads to lower political thresholds for engaging in hostilities. Since the domestic political cost (i.e., risking soldiers' lives) is minimized, decision-makers may be more inclined to use lethal force without exhausting diplomatic or peaceful alternatives.

Summary: Ethical Concerns in Drone Targeting Practices

Ethical Concern	Description	Implication
Individualization	Targeting specific individuals based on surveillance	Enables lawful precision strikes but raises psychological and moral dilemmas
Dehumanization	Viewing targets as data patterns or anonymous threats	Weakens moral accountability and empathy in warfare
Signature Strikes	Based on behavior, not identity	High risk of error; may breach distinction and proportionality
Follow-up Strikes	Attacks on rescuers or funerals	Potential war crimes; damages humanitarian norms
Riskless Killing	Operators face no physical danger	Undermines moral symmetry and encourages escalation of force

In sum, ethical scrutiny reveals that the legality of drone warfare is only one layer of evaluation. The way drone strikes are selected, justified, and executed can lead to moral failings—even if they meet formal legal standards. As drone use proliferates, ethical norms must evolve alongside legal frameworks to ensure that technological advances do not erode the core values that govern armed conflict.

V. Case Study: The Use of Drones in Yemen

The legal and ethical questions surrounding drone warfare become most visible in real-world applications. Yemen serves as one of the most prominent and controversial examples of drone use in modern armed conflict. This case study evaluates U.S. drone operations against al-Qaeda in the Arabian Peninsula (AQAP), the use of drones by Houthi rebels, and the broader implications for international humanitarian law.

1. U.S. Drone Operations Against AQAP

The United States began conducting drone strikes in Yemen in 2002, but operations increased significantly after 2009. Under the Obama administration, Yemen became a key theater in the global campaign against terrorism. According to classified documents revealed in The Intercept's "Drone Papers," the U.S. carried out strikes through Joint Special Operations Command (JSOC) and the CIA, often relying on "kill lists" and pattern-of-life surveillance.

Legal Justifications and Challenges

The U.S. invoked Article 51 of the UN Charter—self-defense—as its primary legal basis for the strikes, targeting individuals linked to al-Qaeda.
In some instances, operations had tacit or formal approval from the Yemeni government. However, after 2017, Yemen’s internationally recognized government publicly requested an end to U.S. strikes, raising serious questions of sovereignty.
The use of force in a sovereign state without consent, outside a declared war zone, challenges the legality of drone use under Article 2(4) of the UN Charter.

Compliance with IHL Principles

While some drone strikes achieved tactical successes, such as the killing of AQAP leaders Nasir al-Wuhayshi and Nasser bin Ali al-Ansi, others resulted in significant civilian casualties.
A 2011 strike targeting Anwar al-Awlaki also killed his 16-year-old son Abdulrahman al-Awlaki in a separate operation—raising doubts about distinction and proportionality.
In a notable incident, a U.S. strike mistakenly targeted a jirga (tribal assembly), killing dozens of civilians. Though initially labeled as militants, later evidence indicated they were local elders resolving disputes.

2. Strategic and Tactical Shortcomings

U.S. reliance on signature strikes and electronic intelligence often led to errors in target identification. A 2013 study by the U.S. ISR (Intelligence, Surveillance, and Reconnaissance) Task Force found:

A lack of full-time surveillance over targets.
Failures in recovering post-strike intelligence due to absence of ground forces.
A tendency to treat drone strikes as tactical ends rather than a component of broader strategy, which reduced long-term effectiveness.

These findings emphasize that even technologically advanced operations may undermine strategic objectives and violate legal standards if intelligence and operational planning are flawed.

3. Impact on Civilian Populations and Radicalization

Drone strikes have had long-term societal consequences in Yemen. Civilian casualties, coupled with the psychological toll of living under persistent aerial surveillance, have:

Fueled anti-American sentiment and contributed to the recruitment capabilities of AQAP.
Undermined U.S. credibility and moral authority.
Resulted in psychological trauma and a breakdown of daily life in targeted regions.

Human rights organizations and UN experts have criticized these operations as being disproportionate and lacking adequate transparency and accountability.

4. Houthi Drone Capabilities and Regional Threats

Since 2015, the Iranian-aligned Houthi movement has increasingly deployed drones against Saudi Arabia and Yemeni government targets. These drones, often modeled on Iranian UAVs such as the Ababil-T and Qasef-1, have been used for:

Targeted strikes, including the 2019 assassination of Major-General Mohammed Saleh Tamah at al-Anad airbase.
Strategic disruption, such as attacks on Saudi Aramco oil facilities and airports.

While rudimentary compared to U.S. technology, Houthi drones present asymmetric threats that challenge conventional military systems and raise new legal issues, including:

The use of drones against civilian infrastructure, potentially violating the principle of distinction.
The proliferation of drone technology among non-state actors, making regulation and attribution increasingly difficult.

5. Civilian Impact: A Quantitative Snapshot

Period	Number of Confirmed U.S. Drone Strikes	Estimated Deaths	Civilians Killed (Est.)
2002–2014	71–83	362–531	64–83
2015–2019 (Trump era)	131 strikes in 2017 alone	Unknown	Increased, less transparency
2020–2022	Decrease in strike frequency	Lower figures	Reduced reporting accuracy

(Source: Bureau of Investigative Journalism; Military Times)

6. Legal and Strategic Conclusions from Yemen

Yemen illustrates the complexities of drone warfare:

Legally, operations often walk a thin line between justified self-defense and violations of sovereignty and IHL.
Strategically, the failure to eliminate threats permanently—combined with civilian harm and instability—can undermine mission objectives.
Ethically, the case raises serious concerns about transparency, due process, and the normalization of remote killings.

The Yemeni context also signals that drone warfare is not immune from political manipulation, intelligence failures, and unintended consequences. Without robust legal checks, accountability mechanisms, and clear operational doctrines, even precision weapons risk becoming tools of long-term destabilization.

VI. Conclusion: Are Drones Legal in Armed Conflicts?

Drones have redefined how modern armed conflicts are fought, offering new tactical capabilities alongside unprecedented legal and ethical challenges. The core question—Are drones legal in armed conflicts?—cannot be answered in absolute terms. The legality of drones under international humanitarian law (IHL) is not determined by the technology itself, but by how states use it within the constraints of well-established legal norms.

Drones can, in principle, comply with the four fundamental IHL principles: distinction, proportionality, humanity, and military necessity. Their ability to conduct prolonged surveillance, reduce direct risk to military personnel, and strike with precision aligns them with legal obligations to minimize civilian harm and avoid unnecessary suffering.

When deployed with accurate intelligence and adequate legal oversight, drone operations can achieve military objectives with fewer casualties than traditional means.

However, Yemen and other operational theaters show how easily these standards can be compromised. The use of signature strikes, follow-up attacks, and operations conducted without the consent of host states reveal a pattern where legal justifications are stretched, and accountability is diminished. Civilian casualties, psychological trauma, and destabilization are real consequences—even when protocols appear to be followed.

Furthermore, the ethical dimension of drone warfare raises serious questions about the normalization of remote killing, the risk of dehumanizing targets, and the expansion of low-cost military engagements with limited public scrutiny. These concerns highlight the growing disconnect between technical compliance and moral responsibility.

To ensure drones remain within the bounds of legality:

States must apply rigorous weapons review procedures under Article 36 of Additional Protocol I.
Independent oversight and transparency must be strengthened to assess strike legitimacy and collateral effects.
International cooperation is essential to regulate the transfer and use of drones, especially by non-state actors.

In conclusion, drones are not inherently unlawful weapons. But they demand a high standard of discipline, transparency, and legal restraint. Their lawful use depends on the capacity and willingness of states to uphold IHL, resist shortcuts in targeting, and prioritize the protection of civilian life even in the pursuit of legitimate security objectives. As drone warfare evolves, so must the global legal framework governing their use.

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