Redefining Air Defense in a New Era
--Europe’s Drone Crisis Poses Challenges for Japan

The repeated incursions of small unmanned aerial vehicles (drones) [1] into the northern and eastern fringes of Europe are not only prompting the strengthening of air defense capabilities, but also the revision and realization of existing air defense concepts.

In September 2025, successive incidents of drone intrusions were confirmed in Poland, Romania, and Denmark, as well as in Estonia, where Russian fighter jets violated Estonian airspace [2]. In response, Poland and Estonia requested formal consultations with the North Atlantic Council (NAC) under Article 4 of the North Atlantic Treaty. NATO strongly condemned Russia's provocative actions[3] and launched Operation “Eastern Sentry”, deploying additional fighter jets, naval vessels, and ground-based air defense assets[4]. Going forward, with technical support from NATO Allied Command Transformation (ACT),[5] the gradual yet steady deployment of anti-drone radars and interception systems to joint forces under the Allied Command Operations (ACO) is expected to take place. Meanwhile, the European Union (EU) also sees this situation as a turning point in terms of security and has launched the “Eastern Flank Watch” project, which centers around a deterrence posture known as a "drone wall."[6] Going forward, NATO and the EU are likely to increase cooperation under a clearer division of roles through information sharing of surveillance and warning data, while avoiding equipment and budget duplication This progress in collaboration is a sign of accelerating initiatives that integrated air defense against emerging airborne threats[7].

Furthermore, during the war in Ukraine, Russia has demonstrated its ability to operate hundreds of drones in coordination with missiles[8], conducting operations that test the limits of Europe's air defense system[9]. This move should be understood as part of a hybrid warfare strategy, which includes not only conventional air and missile defense but also that of information warfare and cyberattacks. Therefore, it is critical for European countries to share the advanced anti-drone combat expertise and technology that Ukraine[10] has developed through actual combat, and to incorporate them into regional air defense networks[11]. These efforts would strengthen the European security system and also could affect the geopolitical balance in the region. The series of drone intrusion incidents has highlighted new challenges for European defense, emphasizing the need for an updated, integrated, and flexible air defense system.

The Evolution of Airborne Threats as Posed by Drones

This incident came as a major shock to European countries not just because drones pose an airborne threat as a new type of weapon, but because it revealed tactical flaws in existing air defense systems[12].

First, drones are marked by their low-cost, high maneuverability, and scalability, enabling mass production for saturation attacks. This forces defenders to expend large amounts of expensive air defense assets[13], potentially devolving the air defense system into a war of attrition, ultimately a struggle for survival. This is why drones are referred to as the "poor man's cruise missile," [14] and airborne threats that exploit this asymmetry in cost-effectiveness have raised security concerns about the effectiveness of air defenses.

Second, drones do not operate independently, but as part of a complex, wave-like attack, often in conjunction with ballistic missiles, hypersonic weapons, and even cyberattacks[15]. As a result, it is becoming increasingly difficult to respond using the traditional method of operating individual air defense assets independently. This will inevitably lead to an accelerated trend toward updating air defense systems that further integrate and coordinate the elements of sensor-based detection, tracking, interception, and command and control.

Third, to deal with these multi-layered and complex airborne threats, we must go beyond the conventional air defense concept of "intercepting after launch." This means that we must shift to a forward defense posture that detects signs of attack at an early stage, identifies the launch source, disrupts it, and neutralizes it[16] Third, to deal with these multi-layered and complex airborne threats, we must go beyond the conventional air defense concept of "intercepting after launch." This means that we must shift to a forward defense posture that detects signs of attack at an early stage, identifies the launch source, disrupts it, and neutralizes it[17].

The emergence of drones as an airborne threat has prompted a redefinition of air defense, not simply as a matter of equipment and interception technology, but as a challenge of intelligence, command, and cross-domain joint operations. This incident once again reaffirms the need for the European security framework to adapt to a new era of air defense.

Major Changes in Air Defense: Integrated Air and Missile Defense (IAMD)

The essence of IAMD is not strengthening individual weapon systems, but organically linking assets across all domains, including land, sea, air, cyberspace, and space, based on information and intelligence, to provide integrated air defense across the entire theater of operations[18]. At the core of this strategy is a multi-layered surveillance and warning system based on the ground and in space. It is essential to develop a command and control (C2) system that can integrate and analyze the vast amounts of data collected by these sensors and use it to make rapid decisions. In particular, strengthening wide-area surveillance using space-based sensors and high-altitude platforms would be highly effective in detecting hypersonic weapons and drones approaching from beyond the line of sight of ground-based radar.

Furthermore, while IAMD tends to focus on intercepting and destroying missiles through kinetic means (intercepting and destroying), efforts are also underway to enhance its deterrent effect by combining it with non-kinetic means (electronic warfare and cyber operations) that can disrupt enemy capabilities before launch[19]. Furthermore, to adapt IAMD to ever-evolving airborne threats and ensure redundancy and flexibility of the entire system, it is essential to actively introduce emerging and disruptive technologies (EDTs)[20]. Artificial intelligence (AI) and image recognition technology will speed up trajectory analysis and threat assessment of swarms of small unmanned aerial vehicles[21], while quantum technology and optimization algorithms will enable more efficient interception decisions and asset deployment[22]. Furthermore, promoting the adoption of dual-use technologies that will utilize commercial satellite communications and civilian sensor networks, standardize data sharing and interoperability, and strengthen supply chains are fundamental requirements for the continued and sustainable operation of IAMD.

To maximize the effectiveness of IAMD, there are limits to what a single nation can do, and public-private collaboration and international cooperation are essential. In Europe, information sharing, coordinated equipment operations, and joint training are being promoted among allied and like-minded countries that have a certain level of military interoperability. These cooperative efforts are expected to enhance deterrence and the sustainability of defending against diverse air threats. The accumulation of such efforts will lead to the development of an integrated air defense system that covers all of the European theater, rather than a localized air defense system.

The Need for Resilience

Airborne threats such as drones not only attack and destroy military facilities, but also pose the risk of causing social unrest and psychological distress, destabilizing critical national infrastructure and the social morale[23]. Therefore, drone intrusion into airspace is not only a military act that can cause physical damage, but also undermines confidence in the existing air defense system and could develop into a political and social issue that can undermine the very sustainability of national defense.

Therefore, rather than simply aiming to completely prevent attacks, it is necessary to consider bolstering "social resilience," or the ability to quickly absorb, mitigate, and recover from damage after it has occurred[24]. This is a concept of national defense that is positioned as an extension of air defense, and refers to a comprehensive approach that includes a nation's crisis response capabilities, such as protecting critical infrastructure, ensuring redundancy in communications and power grids, and strengthening its ability to respond to disasters and cyberattacks. From this perspective, strengthening IAMD is not simply about expanding military technology and equipment, but also about building a national security foundation through the unification of the military, public sector, and private sector. IAMD is not only a defense system, but should also be positioned as a core element of a national strategy to enhance the nation's overall resilience[25].

Policy Implications for Japan

The series of responses in Europe offers many lessons for Japan. First, to respond to the diversifying and complex air threats, it is necessary to accelerate the construction of a seamless air defense network that organically links the sensors, command and control (C2), and interception systems possessed by the Japan Ground, Maritime, and Air Self-Defense Forces, and that also includes the space and cyber domains[26]

Second, it is essential to strengthen societal resilience. This involves enhancing critical infrastructure protection and rapid recovery capabilities, establishing a system for public-private cooperation to maintain communications and satellite services, and combining pre-launch information gathering, intelligence collection, and sanctions to neutralize and minimize enemy airborne threats.

Third, we must prioritize the development of cost-effective, mass-producible non-kinetic weapons and autonomous interception systems, thereby enhancing air defense capabilities that can sustainably respond to saturation attacks by small unmanned aerial vehicles.

To achieve these efforts, it is essential to proactively utilize international partnerships and establish a system in which the public and private sectors work together to promote technological development. At a time when Europe is moving beyond short-term initiatives such as the strengthening of surveillance and troop deployments to revise and accelerate its cross-domain, multi-layered IAMD system, Japan must also act quickly to address the diversification and complexity of air and ground threats in the Asia-Pacific region[27]. Furthermore, the experience and knowledge Ukraine has gained through its warfighting, as well as the institutional and technological frameworks that European countries are developing, will likely provide valuable guidance for Japan as it designs its future air defense and security policies. I understand that Japan is already considering joining the multinational "the Drone Coalition,"[28] but I would like to add that a proactive response is desirable from the perspective of international cooperation in integrated air and missile defense and strengthening of the defense industry.

(2025/11/11)