Drone Warfare in the 21st Century
When was the first known fatal drone strike?
What are some primary functions of UAVs in military operations?
What are some ethical concerns associated with UAV warfare?
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Uncrewed air vehicles (UAVs), colloquially known as drones, have existed since the First World War. Throughout the 20th century they remained something of a niche capability, performing limited surveillance and intelligence roles, notably during such conflicts as the Vietnam War. UAVs were also long used as targets for gunnery and missile-firing practice and testing. But their influence on the broader strategic environment was relatively modest.
The proliferation of drone technology
In the wake of the September 11, 2001, terrorist attacks, the United States rapidly expanded the operational use of UAVs. In Afghanistan, Pakistan, Yemen, and Somalia, UAVs became integral to campaigns targeting such groups as Al-Qaeda and, later, the Islamic State (ISIS). The United States, adapting innovations pioneered by Israel during campaigns in Lebanon and Gaza, deployed such platforms as the General Atomics MQ-1 Predator and MQ-9 Reaper for both reconnaissance and strike missions. These aircraft, equipped with precision-guided munitions, such as the AGM-114 Hellfire missile, demonstrated the potential of uncrewed systems to conduct persistent surveillance and lethal operations over extended periods. An attack on October 7, 2001, in Kandahar, Afghanistan, is often cited as the first fatal drone attack by U.S. forces. This event marked a significant turning point in the use of drones for combat operations and a significant step in the evolution of drone warfare. The incorporation of UAVs into regular military operations marked a paradigm shift in the conduct of warfare, introducing new tactical possibilities, strategic dilemmas, and ethical debates that continue to evolve.
By the mid-2020s UAVs had become so ubiquitous across modern armed forces that nearly every country’s military had at least some form of drone capability. UAV designs range from lightweight, hand-launched reconnaissance drones, such as the Raven RQ-11, to large, long-endurance platforms, such as the Northrop Grumman RQ-4 Global Hawk, which is capable of intercontinental flight and nearly real-time intelligence transmission. Technological advancements have significantly diversified drone capabilities. UAVs may be remotely piloted, semiautonomous, or, increasingly, fully autonomous. Artificial intelligence (AI) and machine learning algorithms allow some UAVs to interpret sensor data, identify targets, and propose or even execute attacks with minimal human input.
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The spread of UAV technology has not been limited to major military powers. Insurgent groups, militias, and groups designated as terrorist organizations have also incorporated UAVs into their arsenals, often adapting commercially available quadcopters and fixed-wing drones for reconnaissance, propaganda, and attack missions. The relatively low cost of entry into drone warfare has disrupted traditional military asymmetries, empowering non-state actors and smaller countries to challenge larger, technologically superior adversaries.
Iran has emerged as a prolific producer of drones across multiple classes. Such systems as the Shahed-131 and Shahed-136 series, classified as one-way attack (OWA) UAVs, have been exported extensively to proxy groups and state allies. Russia, Israel, Ukraine, and Turkey have also developed robust UAV manufacturing capabilities. Turkey’s Bayraktar TB2, in particular, gained international prominence for its operational use in conflicts in Syria, Libya, Nagorno-Karabakh, and Ukraine.
The term one-way attack drone is somewhat vague, blurring the distinction between missiles and UAVs. Likewise, the popular use of the term kamikaze for OWA drones is imprecise: The Japanese word kamikaze translates to “divine wind,” and its original use, certainly by the U.S., referred to the piloted aircraft or missile (baka) suicide attacks used by Japanese Special Attack Units in the Second World War.
Among the most widely used platforms in contemporary conflicts is the Shahed-136, a long-range loitering munition produced under license in Russia as the Geran-2. This system exemplifies the transition from purely reconnaissance platforms to affordable, mass-deployable precision-strike assets. Though often described as loitering, the majority of Shahed variants are more a slow, inexpensive cruise missile substitute than a “true” loitering munition. (A loitering munition is a type of weapon system that sits in the air over an area for a period of time and then strikes a target once it is identified.)
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UAVs serve multiple military functions, including intelligence, surveillance, reconnaissance (ISR), target acquisition, electronic warfare (EW), and precision strike. One of their primary advantages is the ability to maintain persistent surveillance over contested or hostile areas, providing nearly continuous situational awareness. Equipped with high-resolution electro-optical, infrared, and synthetic aperture radar (SAR) sensors, UAVs can detect, track, and monitor enemy movements in real time.
Armed UAVs, or uncrewed combat aerial vehicles (UCAVs), such as the MQ-9 Reaper, can deliver guided munitions. Their ability to loiter for extended periods over target areas allows for dynamic targeting and flexible engagement strategies. Economically, UAVs are attractive alternatives to crewed aircraft. They require lower investment in pilot training, infrastructure, and life-support systems. Maintenance and operational costs are also often substantially lower. This economic efficiency has enabled both well-funded and resource-constrained militaries to develop or procure effective UAV fleets.
The American-made Teledyne Ryan BGM-34A Firebee was likely the first drone to fire a missile, which it did in 1971.
However, UAV warfare raises complex legal and ethical questions. Targeted killings conducted outside formally recognized war zones, particularly by U.S. forces in Pakistan’s Federally Administered Tribal Areas, Yemen, and Somalia, have attracted criticism. Allegations of sovereignty violations, civilian casualties, and lack of due process have prompted debates about the legality and morality of drone warfare under international humanitarian law.
Moreover, the psychological impact of drones on civilian populations is increasingly recognized. Constant UAV presence induces anxiety, fear, and trauma—a phenomenon sometimes described as “drone syndrome.” Populations under continuous UAV surveillance or threat of strike exhibit symptoms akin to post-traumatic stress disorder (PTSD), even without direct exposure to violence.
Also scrutinized were the effects of combat on drone operators themselves. A 2014 study of more than 1,000 U.S. Air Force drone operators determined that more than 4 percent exhibited symptoms of moderate to severe PTSD. The 2026 U.S. National Defense Authorization Act called for additional study of “the prevalence of post-traumatic stress disorder, depression, anxiety, burnout, moral injury, and other mental health conditions” among operators of uncrewed aircraft as well as those who “analyze combat imagery and conduct targeting assessments for such systems.”
Drones in the Russia-Ukraine War
The Russia-Ukraine conflict, initiated by Russia’s full-scale invasion of Ukraine in February 2022 (an extension of Russia’s 2014 invasion of Crimea) has served as a crucible for innovations in UAV warfare. Both sides have made extensive use of drones across the spectrum of military operations, and they have rapidly made adaptations and counter-adaptations.
At the onset, Russia’s indigenous UCAV capabilities were limited. Such systems as the Inokhodets (Orion) and Forpost-R (a licensed Israeli Searcher Mk II derivative) were deployed in small numbers. Ukraine, with limited prewar UAV capabilities, rapidly mobilized domestic innovation and international assistance to build a diversified drone force.
One of the most publicized systems employed by Ukraine was the Turkish-manufactured Bayraktar TB2, which conducted successful strikes against Russian armored columns, supply depots, and air defense systems during the early stages of the invasion. In addition, Ukraine repurposed Cold War-era reconnaissance drones, such as the fighter-sized Tupolev Tu-141 Strizh.
Russia soon augmented its capabilities by acquiring Shahed-131 and Shahed-136 loitering munitions from Iran. Rebranded as Geran-1 and Geran-2, these were mass-deployed against Ukrainian infrastructure, including power grids, command centers, and logistics hubs. The Shahed drones, launched in large numbers, were designed to overwhelm Ukrainian air defenses through saturation tactics.
Innovations observed during the conflict include the use of fiber-optic tethered drones, immune to electronic jamming, and dedicated “drone hunter” UAVs, tasked with intercepting enemy drones. Ukraine has also conducted long-range covert drone strikes launched from within Russian territory, including attacks on strategic airbases using drones concealed in trucks or civilian infrastructure, demonstrating the increasing reach of low-cost UAV systems into deep strategic targets.
Both Russia and Ukraine have also heavily employed first-person view (FPV) drones adapted from commercial racing models. Armed with shaped charges, these low-cost systems have been used to destroy armored vehicles and bunkers with remarkable precision. By the mid-2020s drone warfare had transitioned from a supporting capability to the central organizing feature of battlefield operations, with mass-produced FPV drones, AI-assisted targeting, and drone-on-drone combat fundamentally reshaping the conduct of war.
Defense against drones
The Russia-Ukraine War has demonstrated that drones are capable not only of traditional ISR roles but also of direct action, electronic warfare, and strategic-level attacks, marking a significant evolution in modern warfare. The proliferation of UAVs has necessitated a corresponding evolution in countermeasures. Counter–uncrewed aerial system (CUAS) technologies have become critical components of modern air defense architectures. CUAS methods are broadly categorized into kinetic (in this context, a military euphemism for destructive), electronic, and cyber domains.
Kinetic countermeasures include the use of traditional antiaircraft artillery, such as the ZSU-23-4 Shilka, and man-portable air defense systems (MANPADS), such as the Stinger and Igla-S missiles. In some cases, small arms fire and high rate-of-fire machine guns have proved effective against low-flying drones.
Electronic warfare represents a particularly effective CUAS strategy. Vehicle-mounted systems, such as Ukraine’s Bukovel-AD and Russia’s Repellent-1 use jamming to disrupt UAV communications links and satellite navigation. The Lithuanian-made SkyWiper EDM4S is a handheld jammer with a relatively short effective range (3 to 5 km [1.9 to 3.1 miles]), but its portability and low cost have made it a valuable resource for Ukrainian defenders. GPS jamming and spoofing have proved particularly disruptive against drones reliant on satellite-based guidance.
Dedicated CUASs include
- Drone Dome (Israel): An integrated system for defending against UAVs by using radar, electro-optical sensors, jammers, and, in one variant, a high-energy laser
- SkyWall (U.K.): A handheld system for physically disabling UAVs by capturing them in a net and for controlling their descent to keep them from causing unintentional injuries or damage
- C-RAM (counter–rocket, artillery, and mortar; various countries): Adapted to engage drones with rapid-fire gun systems
Sensor disruption technologies, such as directed-energy weapons and electromagnetic pulse (EMP) devices, are under active development and deployment.
Additionally, novel concepts such as drone-on-drone combat have materialized. Ukraine’s Sting drone, for example, is designed to intercept and destroy loitering munitions mid-flight, effectively operating as a mobile aerial defense asset. Finally, early warning systems employing acoustic sensors, optical trackers, and passive radio frequency detection provide critical situational awareness, enabling timely engagement of incoming UAV threats.
The 2026 Iran-U.S. war
The 2026 Iran-U.S. conflict marked a major escalation in the use of uncrewed systems in modern warfare. Drones became central to both attack and defense operations. Iran relied heavily on low-cost one-way attack systems, especially the Shahed-136. These were used in large numbers against United States and allied bases across the Middle East, including sites linked to Israel. They also targeted radar stations, air defenses, and key logistics hubs.
Iran’s approach highlighted a clear asymmetry in cost and strategy. The Shahed-136 is inexpensive, often costing only tens of thousands of dollars per unit. In contrast, the U.S. and Israel rely on advanced air defense systems such as Patriot, Terminal High Altitude Area Defense (THAAD), and Israel’s Iron Dome and David’s Sling systems. Each interceptor missile can cost millions of dollars. This creates a severe cost-exchange problem. Even when drones are successfully destroyed, the financial burden falls heavily on the defender. This illustrates a widely recognized issue in 21st-century warfare: a reliance on large, expensive, and slow-to-develop and produce weapons, and on hard-pressed production facilities struggling to meet demand.
Iran’s tactic was not only to penetrate defenses but also to overwhelm them. Large-scale drone salvos were designed to force constant interceptions. Over time this risks draining missile stocks and increasing long-term defense costs. The U.S. and Israeli response combined layered air defense, electronic warfare, and greater use of low-cost uncrewed systems. These included one-way attack drones used for precision strikes. Electronic warfare aimed to disrupt drone navigation and communications. Despite this, saturation attacks remained difficult to fully neutralize.
The conflict demonstrated a broader evolution in the nature of warfare. Success is determined not only by advanced technology but also by the ability to maintain defenses against large numbers of relatively inexpensive, autonomous systems. As a result, drone warfare now encompasses significant economic considerations alongside traditional military factors.
Non-state actors and drone warfare
The diffusion of UAV technology has enabled non-state actors to participate in air warfare in unprecedented ways. Organizations deemed terrorist, insurgencies, and militias have adapted commercially available drones for a variety of purposes, including surveillance of enemy positions, coordination of attacks, psychological operations and propaganda, and direct strike missions employing improvised explosive devices (IEDs).
A notable example occurred in September 2019 when drones and cruise missiles were used to strike Saudi Arabia’s Abqaiq and Khurais oil facilities, significantly disrupting global oil supplies. The Houthi movement in Yemen claimed responsibility, though the attack also bore hallmarks of Iranian involvement.
Militant Islamist groups, such as Hezbollah, Hamas, and ISIS, have demonstrated increasing sophistication in their use of UAVs, employing them not only for reconnaissance but also for complex attack operations. ISIS, in particular, during the battle for Mosul, Iraq (2016–17), used drones to drop small munitions on Iraqi forces, marking one of the earliest large-scale military adaptations of commercial drones by a non-state actor.
The democratization of drone warfare complicates traditional counterinsurgency and counterterrorism operations, requiring new doctrines, technologies, and legislative frameworks to confront the evolving threat landscape.
The widespread use of UAVs for targeted killings and strikes raises profound ethical and legal concerns. International humanitarian law mandates the principles of distinction, proportionality, and necessity, but the opaqueness of drone operations, particularly outside active battlefields, challenges these principles.
The absence of due process in targeted killings, combined with the difficulty of independently verifying casualties, has led human rights organizations to accuse drone-operating states of extrajudicial executions. Questions persist about accountability and transparency in drone programs, particularly those operated covertly by intelligence agencies rather than traditional armed forces.
The increasing autonomy of UAVs, enabled by advancements in AI, further complicates the ethical landscape. The prospect of “killer robots” capable of making critical life-and-death decisions independently of human intervention has led to international advocacy for preemptive regulation. Such initiatives as the Campaign to Stop Killer Robots seek, under international law, to prohibit fully autonomous lethal weapons systems.
Future developments
Several trends are expected to shape the future of UAV warfare:
- Human-machine teaming: Such programs as the U.S. Air Force’s loyal wingman initiative envision UAVs operating alongside crewed aircraft, extending sensor reach, increasing firepower, and absorbing risk in contested environments.
- Swarm tactics: The deployment of large numbers of networked drones acting in concert could overwhelm enemy defenses. Swarming technology leverages distributed AI to enable autonomous coordination and decision-making.
- Autonomous refueling: Such platforms as the Boeing MQ-25 Stingray aim to provide aerial refueling to both crewed and uncrewed aircraft, increasing the operational range and endurance of strike and reconnaissance assets.
- Hypersonic UAVs: Research into hypersonic (five or more times the speed of sound in air) flight regimes could produce UAVs capable of unprecedented speed, survivability, and worldwide reach.
AI seems likely to continue enhancing UAV capabilities, enabling increasingly sophisticated autonomous functions, faster decision cycles, and increasingly independent mission execution. However, this evolution will heighten concerns regarding accountability, reliability, and unintended escalation.
The advantages of uncrewed air systems are considerable, making it likely that they will remain essential to military operations for many years to come. At the same time, the ethical, legal, and strategic challenges posed by UAVs call for careful international dialogue and regulation. As technology continues to advance, drone warfare will likely become more autonomous, more widespread, and more decisive, fundamentally altering the way battles are fought. It has also changed the balance of power, with countries and nonstate actors that are better able to adopt and evolve their own drone use, proving hard to counter by nominally more powerful countries using more traditional means.