Introduction

Drones have become a dominant force in Russia's war against Ukraine, with their numbers reaching unprecedented levels. In May 2024, Ukraine's military leadership indicated that drones were the leading cause of casualties on both sides, stating that 'drones kill more soldiers than any other weapon'. At the start of 2024, Ukraine aimed to produce 1 million drones, later raising the target to 4 million annually; Russia is reportedly keeping pace. Over 100 drone variants are in use, ranging from small hobbyist models to large, nearly 20-metre-wide unmanned aircraft. These drones serve multiple purposes, including reconnaissance, targeted strikes and guidance for other weapons systems. They are also used as decoys, communication relays and transport tools. Both nations manufacture their own drones, adapt civilian models, or source them from allies.

The war's conditions have made drones essential, particularly as manned aircraft face strong air defences. Amidst Ukraine's ammunition shortages, drones have played a crucial role in sustaining its defence. Beyond aerial systems, Ukraine has deployed naval drones to target Russia's Black Sea fleet, successfully sinking several vessels. The country is working towards developing a dedicated fleet of these unmanned warships. Ground-based drones, while less advanced, are also being used for transport, reconnaissance and limited attacks.

However, drones are not only prevalent in the war in Ukraine; they are now a common feature in conflicts worldwide, playing a significant role in the wars in Gaza, Israel and Lebanon, in the civil wars in Yemen, Sudan, Syria and Myanmar, and in the attacks on international vessels in the Red Sea. Their use is also expanding among non-state groups in the Middle East and Africa. Some view this trend as a ground-breaking transformation in warfare, while others consider it a natural progression of military technology.

History of drones and their strategic impact

The history of unmanned flight dates back approximately 180 years, when Austria used explosive-filled balloons in an attack on Venice. In the early 20th century, the Wright Brothers – pioneers of manned aviation – also conducted unmanned flight experiments. By World War I, military strategists were already considering how to incorporate unmanned aircraft into warfare, and drone technology continued advancing through World War II. Nikola Tesla played a key role in the development of unmanned systems with his invention of a radio-controlled boat, which later influenced drone technology. By 1998, the first drone had successfully completed a transatlantic flight, covering the distance in nearly 27 hours using just 5.6 kg of fuel.

Since the early 2000s, the United States (US) has conducted thousands of long-range drone strikes against high-value targets worldwide as part of its Global War on Terror. The conflict in Ukraine differs because of its extensive and diverse deployment of drones, which are constantly present over the frontlines, complicating troop and vehicle movements. In addition to frontline surveillance and attacks, drones are also being used for long-range strikes deep behind enemy lines, targeting airbases, naval shipyards and civilian infrastructure such as energy facilities and residential areas.

While drones have undeniably altered the tactical dynamics of warfare, their broader strategic impact remains uncertain. Despite decades of US drone strikes in the Middle East and Afghanistan, militant threats persist. Similarly, the large-scale use of drones in Ukraine by both sides has not significantly altered the frontlines, raising questions about their long-term effectiveness in shifting the course of a conflict. The effectiveness of drones is heavily influenced by the defences deployed against them. Large aerial drones are susceptible to patrolling aircraft and surface-to-air missiles at high altitudes, while smaller quadcopters can be taken down by radar-guided anti-aircraft guns or even basic firearms at lower altitudes. Additionally, drones are vulnerable to electronic warfare (EW), which can disrupt their communication and navigation systems. Physical defences, such as nets and metal cages, also help mitigate the impact of drone attacks.

According to experts from the European Union for Security Studies (EUISS) 'Drones may not be a magic bullet that will single-handedly turn the tide of war, but they are here to stay'. They note that the ability of drones to combine surveillance and strike capabilities at a relatively low cost has made them indispensable. Countries across Europe and beyond, including the EU, are closely observing and learning from Ukraine's experience to refine their own strategies.

Definitions and types of drones

Unmanned aircraft, commonly known as drones, are described using various terms such as unmanned aerial vehicles (UAVs), remotely piloted aircraft systems (RPAS), and unmanned aircraft systems (UAS). While these terms broadly describe the same concept, they highlight different components. For example, an unmanned aircraft refers to any aircraft that operates without a pilot on board, whereas an RPAS includes additional elements such as a remote pilot station and command-and-control functions. A UAS, as a complete system, consists not only of the unmanned aircraft itself but also a ground-based controller and a communication platform. Another category within the drone family are the lethal autonomous weapons systems (LAWS), sometimes controversially labelled as 'killer robots'. Although all the above are often grouped under the umbrella term 'armed drones', a key distinction exists: armed drones allow human intervention while LAWS operate entirely autonomously. While drones technically fit within the broader definition of 'robots', this term extends beyond unmanned aircraft to include a wide range of industrial applications. Moreover, although drones are most commonly associated with aviation, they are also used for land and maritime operations. Drones have both military and civilian uses (see Figure 1).

Source: EPRS briefing, 2019.

In military contexts, the term 'drone' has traditionally been used to refer to remotely controlled aircraft used for gunnery practice. However, the definition has expanded significantly in recent years to include a wide range of devices, from inexpensive, weaponised recreational multicopters to sophisticated, jet-sized uncrewed aircraft designed for intelligence, surveillance and reconnaissance (ISR), some of which cost millions.

The rapid proliferation of drones is particularly evident in the conflict in Ukraine, where both sides deploy thousands of drones of various sizes and types daily. While aerial drones (UAVs) are the most common, maritime drones have made a significant impact in the Black Sea, and land drones (uncrewed ground vehicles – UGVs) are increasingly appearing on the battlefield. Drones can be armed or unarmed, deployed for ISR or direct action, and either recoverable or designed as one-way-attack (OWA) drones that self-destruct upon impact. Some drones are remotely piloted using first-person view (FPV) goggles, while others are programmed as loitering munitions to autonomously seek out pre-designated targets. A growing trend in drone warfare is the treatment of certain OWA drones as expendable munitions, like artillery shells, while others function more like cruise missiles. Additionally, new and niche applications are emerging, including drone-based mine deployment, aerial combat through direct collision, and even UAVs equipped to breathe fire. The evolving roles of drones in modern warfare underscore the increasing complexity of their use and their expanding presence across various domains.

Drones vary significantly in size and design, ranging from insect-sized models to massive aircraft weighing several tonnes. Those weighing less than 2 kg are categorised as 'micro' or 'nano' drones, while those under 20 kg fall into the 'mini' category. Drones exceeding 20 kg are considered 'small' and are typically launched by hand or using a catapult. Medium-sized drones, weighing between 150 kg and 600 kg, are mainly used for military purposes, while large drones, exceeding 600 kg, are exclusively deployed in military operations. Military forces deploy drones of various sizes and weights, but most armed drones are significantly larger than standard commercial models, often exceeding 600 kg. Smaller drones can also be modified or designed to carry weapons or serve ISR roles, with nano and micro drones frequently used for intelligence gathering. Large drones typically operate beyond the visual line of sight, sometimes relying on radio transmission to relay imagery to operators. Medium-altitude long-endurance (MALE) and high-altitude long-endurance (HALE) drones are classified as large drones, capable of supporting tactical ISR missions as well as battlefield operations and targeted strikes. However, highly advanced military drones like the RQ-4 Global Hawk are primarily designed for ISR functions, and even drones commonly used for strikes often have unarmed ISR variants. Drones can be operated remotely or navigate autonomously using programmed instructions or artificial intelligence (AI). They come in different types, including single-rotor, multi-rotor, fixed-wing, and hybrid vertical take-off and landing (VTOL) models.

Drone swarms – defined as coordinated systems of multiple drones operating autonomously with minimal human oversight – are another ground-breaking technology. They leverage AI and machine learning to navigate challenges like GPS jamming and adverse conditions. Their cost-effectiveness and versatility offer significant advantages over traditional military deterrents, enabling synchronised operations across various domains. Globally, countries such as the US, China and several European countries are advancing drone swarm technologies, recognising their transformative impact on modern warfare strategies.

While fully autonomous military drones capable of selecting and engaging with targets without human input are not officially deployed at scale, there is growing evidence that such systems have been used in limited conflict scenarios. For instance, a United Nations report suggested that the Turkish-made Kargu-2 drone may have operated autonomously during a 2020 conflict in Libya, marking a possible first use of lethal autonomous weapons in combat. Drones like Israel's Harpy are also designed to autonomously detect and destroy radar emitters. Meanwhile, organisations like the International Committee of the Red Cross (ICRC) and Stop Killer Robots are pushing for global rules to ensure meaningful human control remains in place.

The EU and drones

In March 2022, at Versailles, EU leaders committed to substantially increasing defence expenditure. They also pledged to invest in critical and emerging technologies, such as drones, and in innovation for security and defence purposes. Additionally, they vowed to foster synergies between space, civilian and defence innovation and research. These commitments were later reiterated in the Strategic Compass.

The March 2024 European defence industrial strategy (EDIS) also calls for increasing defence innovation and the capacity to scale up production of affordable unmanned systems as a key requirement for EU defence preparedness in high-intensity conflicts. It notes that the European defence industry programme (EDIP) – which is currently pending negotiation and adoption by the European Parliament and the Council of the EU – could focus on enabling mass production, addressing supply chain vulnerabilities and removing critical dependencies. Joint procurement of drones or counter-drone systems may also be supported under the European Defence Industry Reinforcement through Common Procurement Act (EDIRPA). Furthermore, it suggests that Ukraine's urgent need for unmanned aircraft systems could be addressed through the European Peace Facility, in coordination with allied efforts through the Ukraine Defence Contact Group (a coalition of 57 nations, including all 32 NATO member states and the EU, supporting the defence of Ukraine). It also refers to the Commission's drone strategy 2.0 of November 2022. Key initiatives within it include coordinated EU-European Investment Bank (EIB) funding for a flagship drone technologies project, the creation of a strategic drone technology roadmap to guide research and reduce dependencies, and the establishment of a civil-defence drone testing network to foster collaboration across sectors. In addition, the EDIS notes that the Commission will put forward a policy proposal to support the production of drones within the EU or possibly jointly with Ukraine by mobilising relevant instruments.

Uncrewed systems across all domains, including the weaponisation of existing platforms, feature prominently in the EU capability development plan (CDP), which was approved by EU defence ministers in 2023. Notably, the CDP also advocates for the development of a European, NATO-interoperable standard for air defence systems, encompassing both kinetic and directed energy technologies designed to counter 'slow, small, and low-altitude threats' as well as drone swarms.

The ReArm Europe plan/Readiness 2030, launched by Commission President Ursula von der Leyen, aims to bolster EU defence capabilities by leveraging over €800 billion in funding. EU Member States are encouraged to increase national defence spending by activating the Stability and Growth Pact's escape clause, allowing temporary fiscal flexibility for up to four years, limited to defence expenditure and capped at 1.5 % of GDP annually. A new €150 billion instrument, SAFE (Security Action for Europe), should provide long-term EU-backed loans to support rapid and large-scale defence investments, mainly through joint procurement, with participation extended to Ukraine, EFTA/EEA countries, and EU partners. The plan also leverages the EIB Group and introduces a new savings and investments union strategy to attract private capital, ensuring the long-term viability of the EU's defence industrial base.

The white paper for European defence – Readiness 2030 identifies drones and counter-drone systems as one of seven priority areas critical for building robust EU defence. It emphasises that collaborative procurement is the most efficient means to acquire large numbers of drones. Additionally, the paper highlights Ukraine's significant expertise in drones and suggests that drones should be provided to Ukraine as a priority, as they are essential to address the asymmetry in military resources on the battlefield.

At the special European Council meeting on 6 March 2025, EU leaders reaffirmed their commitment to strengthening defence capabilities and autonomy in response to security threats, more specifically Russia's war against Ukraine. Recognising the urgency of the situation, they welcomed the Commission's plan to recommend activating the Stability and Growth Pact's escape clause to enable increased national defence spending. Additionally, they took note of the SAFE proposal for €150 billion in defence loans. Leaders also backed expanding the EIB's role in defence financing and called for private sector mobilisation. They urged simplification of legal and administrative frameworks and stressed the need to reduce strategic dependencies while boosting the EU's defence industry (a dedicated defence omnibus simplification proposal is expected by June 2025, according to the white paper). At the 20 March meeting, leaders emphasised the swift implementation of these initiatives, underlining the EU's complementary role to NATO in strengthening global and transatlantic security.

Drone regulation

The increasing use of drones in modern warfare – highlighted in conflicts such as the one in Ukraine, the Red Sea, and the Israel-Hamas war – has brought a host of legal and ethical challenges to the forefront. In the case of civilian drones, the Commission has been developing a comprehensive drone policy for over a decade. In 2014, it proposed a regulatory framework for various drone types and uses, with the European Aviation Safety Agency (EASA) taking the lead in setting common standards. The 2015 aviation strategy expanded this work, instructing EASA to draft detailed regulations and safety protocols. A 2018 regulation extended EU aviation rules to all unmanned aircraft, addressing safety, privacy, liability and environmental concerns. In 2019, drones were classified into open, specific and certified categories with distinct requirements. These rules, implemented in 2020, helped make the EU a leader in drone regulation. The 2021 U-space regulations, effective since 2023, aim to safely integrate drones into airspace through technical rules, coordination mechanisms and electronic visibility for aircraft. The 2022 drone strategy 2.0 seeks to expand drone usage and regulation across the EU by 2030. It focuses on building a strong drone ecosystem, with 19 flagship actions across nine areas, including innovative air mobility, public acceptance, training, investment, research, and system resilience.

The EU does not directly regulate military drone use in the same way as it regulates civilian drones. Military operations, including the use of drones for defence purposes, remain within the exclusive competence of the individual Member States. The regulatory framework governing armed drones spans three key areas of international law: international humanitarian law, international human rights law, and the law governing the use of force. Notably, the UN Convention on Certain Conventional Weapons, adopted in 1980, plays a significant role. The convention established the Group of Governmental Experts (GGE) to address emerging technologies, including LAWS, and to consider the ethical and moral issues surrounding their use in armed conflict. Discussions primarily focus on the human element involved in deploying such technologies and the responsibility in case of accidents. However, these forums have faced criticism for being too slow and unwieldy to handle effectively the rapid advancements and complex technological challenges involved.

In 2013, Christof Heyns, then the UN Special Rapporteur on extrajudicial, summary, or arbitrary executions, submitted a paper to the UN General Assembly detailing the international legal standards governing the use of armed drones. Essentially, it asserted that, for drone strikes to be considered lawful, they must comply with legal criteria in three main areas: the rules on the use of force, international humanitarian law, and international human rights law. The ICRC agreed that drones themselves do not inherently violate these principles, and that what matters is how they are used. In practice, however, applying these legal principles can be highly complex. Drones can theoretically enable more precise targeting, yet in many cases long-range drone attacks miss intended targets and result in civilian casualties. This raises questions about the obligation to distinguish between combatants and civilians and to avoid indiscriminate attacks. Energy infrastructure, for instance, has become a common target in Ukraine, prompting debate over whether such facilities are civilian objects or legitimate military objectives. Experts like Michael Schmitt argue that if disabling energy systems yields a clear military advantage – such as halting fuel supplies – they can be lawful targets, but only if the civilian harm is not excessive.

The principle of proportionality is central here. Civilian harm must not be disproportionate to the anticipated military gain. In cases where power outages caused by drone strikes lead to loss of life due to lack of medical care or heating, such attacks may be deemed unlawful. Legal scholars like Katharine Fortin stress that widespread civilian suffering, even if unintended, may still breach international legal standards. Moreover, the use of drones for what are referred to as 'personalised' strikes – targeting individuals – raises the issue of extrajudicial killings. Even when targeting combatants, drones must comply with legal safeguards. There must be an imminent threat and no viable alternative to lethal force. Concerns also persist around drone operators' reliance on visual data, which can be misinterpreted, especially in conflicts involving insurgents who may appear indistinguishable from civilians. Studies have shown that image-based targeting can introduce cognitive bias, further complicating legal compliance. There is also a moral and legal dilemma regarding surrender. ICRC guidance suggests that combatants must be allowed the opportunity to surrender where possible. Yet drones are often used to strike without warning, giving targets minimal chance to surrender. While footage of soldiers surrendering to drones occasionally circulates, the dominant narrative is one of lethal force being delivered remotely and instantaneously. Despite drones falling within the scope of existing legal regimes, enforcement has not kept pace with technological developments. Legal scholars and humanitarian organisations continue to raise concerns that the current use of drones – especially autonomous or semi-autonomous systems – may outstrip the ability of existing laws to regulate them effectively.

The UN's New Agenda for Peace has highlighted the critical need for strong governance frameworks to regulate emerging military technologies. The ICRC defines autonomous weapons as systems with 'critical function' autonomy, allowing them to independently select (i.e. search for, detect, identify, and track) and attack (i.e. intercept, neutralise, damage, or destroy) targets. These AI-powered systems, which may not be adequately vetted by decision-makers, raise serious concerns regarding accountability, proportionality and compliance with international humanitarian law. Since 2018, UN Secretary-General António Guterres has denounced LAWS as 'politically unacceptable and morally repugnant', calling for their prohibition under international law. The United Nations' Group of Governmental Experts on Lethal Autonomous Weapons Systems (GGE LAWS) continues to examine the ethical and security concerns surrounding these technologies. This forum, which brings together UN member states, NGOs, industry representatives and researchers, aims to establish common principles for the governance of autonomous weapon systems. In October 2023, the UN General Assembly adopted a resolution highlighting the potential threats posed by LAWS to global security and stressing the urgent need for a coordinated international response.

The EU, as a strong advocate for peace and human rights, plays an active role in these discussions. Several EU Member States have been instrumental in advancing the UNGA resolution, and the EU actively engages in the GGE on LAWS. Additionally, the Commission and the Parliament set up a working group on UAS prior to the publication of the drone strategy 2.0., outlining guidelines for the responsible use of drones in both civilian and military contexts. However, within the EU – and even more so on a global scale – there is no consensus on whether fully autonomous weapons should be regulated, particularly regarding the conditions under which they may be deployed and the responsibilities of their operators. Despite growing awareness of the ethical, legal, and security risks associated with autonomous drones in warfare, the EU has yet to develop a unified and coordinated international strategy to address these concerns.

European Parliament's position

Parliament has articulated a cautious stance on military drones, emphasising strict adherence to international law, particularly international humanitarian law and international human rights law. It has expressed grave concerns over the use of armed drones outside the international legal framework, especially regarding extrajudicial targeted killings, which it deems a violation of international law and a potential act of aggression when conducted without the consent of the targeted state's government. Parliament has called for the EU and its Member States to oppose and ban the practice of extrajudicial targeted killings, ensure that Member States do not perpetrate or facilitate unlawful targeted killings and include armed drones in relevant arms control and disarmament regimes. Additionally, Parliament advocates for transparency and accountability in drone operations, urging prompt, independent investigations into allegations of civilian casualties and public disclosure of the results. It also calls for strict controls over drone exports to prevent their use in human rights abuses. These positions reflect Parliament's commitment to ensuring that the use of military drones aligns with international legal standards and ethical norms.

Parliament has also taken an early and active role in the military AI debate, adopting key resolutions in 2018 and 2021. While generally open to military AI for its strategic value and potential to protect lives, Parliament stresses three core principles: human control, legal accountability and international governance via the UN. It strongly opposes LAWS without meaningful human oversight and calls for their global ban through UN negotiations. The 2021 resolution urges an EU-wide framework to regulate military AI in line with international law and fundamental rights, promoting ethics, transparency and accountability. Though the EU AI Act, adopted in 2024, excludes military uses, Parliament's Artificial Intelligence in the Digital Age (AIDA) Committee has nevertheless addressed dual-use concerns, highlighting the need for responsible AI governance in defence and cybersecurity, as well as cooperation with partners like NATO.

At the same time, Parliament actively supports defence innovation, particularly in the development and integration of UAS and emphasises the importance of fostering a competitive and innovative defence industrial base to enhance the EU's strategic autonomy. Parliament has called for the Commission to propose an EU drones package focusing on drone and anti-drone systems, including plans and funds to stimulate R&D. This initiative aims to learn from the Ukrainian experience and be open to the participation of Ukraine's highly innovative companies in R&D. It also aims to establish an industrial programme dedicated to the joint development, production and procurement of drones and anti-drone systems, as well as a regulation on the use of drones in civilian and military contexts. Additionally, Parliament has advocated for increased funding and support for emerging disruptive technologies in defence, recognising their potential to revolutionise military operations. Through these efforts, Parliament seeks to ensure that the EU remains at the forefront of defence technology and enhances its security and defence capabilities.