Efficient maritime counter-UAV operations require the establishment of a complete kill chain consisting of detection, identification, tracking and hard-kill interception. Every link in this chain must be tailored to the physical characteristics and attack-defense cost profiles of Tier 2 maritime UAV threats. This paper breaks down the technical selection logic for each link one by one, covering why only active phased array radars can meet detection requirements, the core performances that electro-optical targeting systems must possess, and a comparison of the advantages and disadvantages of various mainstream kill equipment in counter-UAV missions.

Counter-UAV operations constitute an independent combat domain with unique physical threat characteristics, attack-defense cost logic, and adaptability requirements for combat platforms. The analysis in this paper is built on two core principles. First, forward deployment is critical: if threats approach from the sea, defense cannot be confined to coastlines. Effective maritime counter-UAV operations demand forward defense to conduct layered interception along incoming threat flight paths. Second, layered and overlapping defenses create defense depth. The three-tier operational framework—Tier 1 counter-small UAVs, Tier 2 maritime counter-UAVs, and Tier 3 air defense operations—validates the reality that a single system cannot cover the full spectrum of threats. Accordingly, a system centered on Tier 2 maritime counter-UAV capabilities, while concurrently supporting Tier 1 missions and addressing low-end Tier 3 threats, can establish a multi-layered, three-dimensional in-depth defense system.

I. Core Dilemmas of the Kill Chain
Infographic of Maritime Anti-UAV Kill Chain
To counter Type III U.S. Department of Defense / Type II NATO maritime unmanned aerial vehicles (UAVs), a complete end-to-end kill chain must be executed within an extremely tight time window. Detection ranges must provide ample operational response lead time; the identification phase needs to accurately judge the hostile affiliation of targets; the tracking phase must continuously output high-precision fire-control-grade data; and hard-kill interception must fully neutralize UAVs before they reach protected assets.
Failure at any single link of the kill chain will render the entire defense system completely inoperative. Sensors capable of detection yet unable to sustain tracking, electro-optical systems that can identify targets but cannot conduct laser boresighting, and interception equipment with insufficient kill probability or slow response will all ultimately result in target penetration. For assets such as ports, energy facilities, and anchored warships, penetration by even a single UAV may deliver a crippling strike. Therefore, technical selection does not aim for peak performance of individual devices alone; instead, it focuses on building a complete, compatible, closed-loop operational chain that accounts for operational platform constraints, cost budgets, and interception time limits.

II. Detection and Tracking: The Primary and Most Challenging Technical Bottleneck
Detection challenges stem from two overlapping factors: target radar cross-section (RCS) and operational platform payload limitations. Type II maritime UAVs can feature an RCS as low as 0.1 square meters, making them nearly undetectable by conventional air search radars. Large ship-borne active phased array radars can pick out targets with RCS as low as 0.01 square meters, yet such equipment is designed exclusively for major capital warships. Their excessive weight, power consumption, and procurement costs prevent mass deployment and forward emplacement, disqualifying them as routine maritime screening and detection assets.
To establish an unbroken detection barrier along maritime threat axes, lightweight sensors suited to the dimensional, weight, and power constraints of medium and small unmanned surface vehicles (USVs) that support mass fielding are required.
ULAQ-11 Unmanned Surface Vehicle Firing Dual Cirit Semi-Active Laser-Guided Missiles During Exercises
Passive detection equipment (radio frequency direction-finding sensors, acoustic sensors) carries fundamental flaws: they cannot generate the high-precision three-dimensional tracking data required for fire control. Meanwhile, advanced autonomous maritime UAVs operate in full radio silence with zero signal emissions during terminal flight, rendering passive sensors entirely blind to targets. As such, passive detection is only viable for defending against Type I small UAVs or serving as a supplementary early warning measure, and cannot undertake core detection missions.
Compact active phased array radars purpose-built for counter-UAV missions resolve all the above limitations. Modern lightweight active phased array radars can stably detect and track targets with RCS as low as 0.01 square meters within the payload limits of medium and small USVs. Equipped with full 360° coverage and track-while-scan multi-target engagement capabilities, these radars operate reliably amid harsh, volatile meteorological conditions and accommodate UAVs across all speed classes, from low-speed piston-powered to jet-powered variants, establishing them as the core detection asset for Type II maritime counter-UAV operations.
*Note: Stated detection ranges represent typical operational figures for targets with a 0.1 m² RCS in maritime combat environments.*

III. Identification and Fire Control: Electro-Optical Sighting Systems
Active phased array radars handle search and target tracking, while electro-optical (EO) systems execute target identification and fire-control boresighting under radar cueing via a three-stage workflow: automatic slewing and visual target acquisition, high-definition imagery output to validate hostile target affiliation, sustained fire-control data transmission (via coded laser boresighting or seeker data handover), and post-interception damage assessment.
In complex maritime environments, UAV targets measuring 2.5 to 3.5 meters in length must be positively identified at distances of 5 to 10 kilometers. This mandates EO systems fitted with stabilized gimbals capable of sub-pixel-level precision tracking amid Sea State 4 deck motion, alongside automated radar target handover functionality to meet the stringent response timelines for rapid interception. Reliable all-domain combat performance relies on multi-spectral configurations: daylight high-definition cameras deliver maximum identification accuracy under clear weather; mid-wave infrared channels penetrate darkness, fog, and smoke; short-wave infrared channels mitigate interference from marine aerosols and high-humidity conditions.
Selection between high-end integrated EO systems and mid-tier compact EO sighting units hinges on the type of hard-kill ordnance integrated aboard the platform. Vessels armed with semi-active laser-guided missiles require coded laser designators and high-stability gimbals to maintain continuous target illumination throughout missile flight. Platforms fielding infrared / imaging infrared fire-and-forget munitions may utilize mid-tier EO systems, which only need to conduct target cueing and lock confirmation.
*Note: This table outlines core performance metrics for EO sighting systems supporting Type II maritime counter-UAV operations; selection between high-end and mid-tier variants is determined by the platform’s integrated fire-control architecture and hard-kill ordnance suite.*

IV. Comparative Analysis of Hard-Kill Equipment Suites
The core logic governing hard-kill asset selection lies in balancing kill probability against the cost-exchange ratio of attack and defense, tailored to operational scenarios involving mass UAV saturation strikes. Interception costs per engagement span eight orders of magnitude across different equipment types: electronic countermeasure (ECM) systems cost roughly $0.01 per interception, while advanced air defense interceptors carry a unit cost as high as $4.75 million. This drastic cost disparity translates to fundamentally distinct operational economic models, and all hardware must be evaluated for compatibility against the real-world operational parameters and budgetary demands of Type II counter-UAV missions.
1. Advanced Air Defense Missiles (Patriot PAC-3, NASAMS, IRIS-T SLM): Boast extremely high kill probabilities, yet against UAVs priced at $20,000 to $50,000 apiece, they yield a defense-to-offense cost exchange ratio exceeding 100:1, imposing prohibitive financial burdens on defensive forces. Additionally, their substantial weight and power draw render them incompatible with small USVs, restricting deployment exclusively to Tier III long-range air defense missions and disqualifying them for Type II counter-UAV duties.
2. Programmable Air-Burst Naval Gun Systems: Deliver compelling per-interception cost advantages, yet small-caliber naval guns suffer from insufficient effective range, while large-caliber rapid-fire naval guns impose unmanageable weight and power loads for USV integration. Their 3–5 kilometer effective range offers minimal margin for error; a failed primary interception virtually eliminates opportunities for secondary engagements. These systems are only suitable for large warships and fixed shore emplacements, and cannot support forward-deployed USV screening and defense.
3. Electronic Warfare (EW) Systems: Prove highly effective against Type I small UAVs dependent on manual piloting and satellite navigation, yet are largely ineffective against Type II autonomous maritime UAVs guided by inertial navigation, hardened satellite navigation, terrain matching, and AI vision-based autonomous navigation. The industry trend toward fully autonomous terminal flight for modern UAVs strips EW systems of core functionality for Type II counter-UAV missions, relegating them solely to auxiliary support roles.
4. Directed Energy Weapons: Feature near-zero per-interception costs and unlimited virtual magazine depth, promising broad long-term operational utility. However, sustained combat operation requires power outputs in the hundreds of kilowatts—a threshold medium and small USVs cannot currently satisfy. Furthermore, maritime atmospheric conditions attenuate and scatter laser beams, drastically degrading combat effectiveness. This technology remains in iterative maturation and lacks full operational viability as a primary hard-kill asset at present.
5. Interceptor UAVs: Carry low per-interception costs, yet propeller-driven interceptor UAVs top out at speeds below 300 kilometers per hour, creating an inherent velocity limitation that prevents engagement of jet-powered maritime UAVs traveling 500–650 kilometers per hour. Even upgrades incorporating rocket propulsion to boost speed push their form factor and procurement costs close to precision-guided missiles, erasing their original cost advantages. Maritime combat lacks topographical cover to establish layered interception barriers; additionally, hit-and-fly interceptor UAVs rely on manual piloting and lack autonomous target handoff capabilities, imposing a hard ceiling on interception efficiency when facing mass UAV saturation attacks.

V. Optimal Kill Solution: Lightweight Precision-Guided Missiles
Comprehensive cross-comparison of all technical solutions yields a definitive conclusion: Tier III air defense missiles generate unsustainable costs when countering mass UAV assaults; naval guns and directed energy weapons are constrained by physical limitations and technological immaturity, barring integration aboard small unmanned combat platforms; interceptor UAVs and EW systems suffer operational failure due to the speed edge and autonomous terminal flight capabilities of Type II UAVs. Only lightweight precision-guided missiles utilizing semi-active laser and infrared / imaging infrared guidance deliver superior overall performance, combining high kill probability, rapid response, and controllable defense-offense cost ratios, with proven operational validation on USV platforms.
The two missile variants deliver tactical complementarity: semi-active laser-guided missiles offer a maximum interception range of 5 kilometers and can sequentially engage multiple targets on a single sortie to sustain continuous operations. Infrared / imaging infrared missiles operate in fire-and-forget mode with a maximum interception range of 8 kilometers; post-launch, the EO system is freed from target lock to immediately initiate the next interception sequence, enabling efficient neutralization of UAV saturation strikes. Co-launcher integration of both missile types offsets the tactical shortcomings of single-variant ordnance and establishes a complete layered interception architecture.

VI. Core Conclusions
End-to-end analysis of the full kill chain produces three definitive findings:
1. The detection phase must rely on compact active phased array radars. Conventional mechanically scanned radars cannot achieve low-RCS target detection and multi-target tracking within USV payload constraints, failing to meet the operational requirements of modern maritime counter-UAV warfare.
2. The identification and fire-control phase must adopt integrated multi-spectral EO systems covering daylight, mid-wave infrared, and short-wave infrared bands. Single-channel EO hardware cannot adapt to complex sea states, nocturnal operations, and high-humidity maritime atmospheric environments, and will readily fail under real combat conditions.
3. The optimal hard-kill solution available today is a co-launched combined suite of semi-active laser-guided and infrared / imaging infrared lightweight missiles. This remains the sole hard-kill ordnance combination that concurrently satisfies three core criteria: sustainable operational costs, technological maturity, and compatibility with unmanned surface vehicle platforms.

Against the prevailing threat posed by Type II maritime UAVs, the conclusion is unambiguous: the capacity of maritime counter-UAV operations to close the kill chain and eliminate target penetration hinges entirely on whether deployed sensors and hard-kill assets are precisely calibrated to the physical characteristics and cost dynamics of Type II UAV threats.