Can Microwave Weapons Stop Threats at Sea?

Introduction

Leonidas H2O represents a significant shift in the Leonidas family of directed-energy weapons. Earlier Leonidas systems were primarily associated with defeating drone swarms by disrupting their electronics with high-power microwave (HPM) energy. Leonidas H2O extends that same counter-electronics concept into the maritime domain, targeting small boats, unmanned surface vessels (USVs) and aerial drones with a common microwave effect. The key development is not simply that the system can operate near water; it is that it demonstrated the ability to disable outboard boat motors during US Navy testing, addressing a long-standing requirement for a non-kinetic vessel-stopping capability. [Epirus+2Naval News]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

Within the broader evolution of Leonidas variants, H2O shows how a microwave weapon originally designed for counter-UAS missions can be adapted to maritime interdiction. Rather than shooting down threats, it seeks to disrupt the electronic systems that make them function, whether those systems are inside a drone, an autonomous surface craft or a small fast boat. [Epirus+2DefenseScoop]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

Why Maritime Threats Changed the Target Set

Naval and coastal forces increasingly face threats that blur the line between aircraft and vessels. Small unmanned surface vessels, remotely operated explosive boats, autonomous reconnaissance craft and low-cost fast attack boats all rely heavily on electronic control systems. At the same time, many maritime operations must contend with aerial drones operating above the water. [DefenseScoop]defensescoop.comepirus navy hpm microwave antx coastal tridentNavy to test Epirus high-power microwave's ability to zap…4 Apr 2024 — The Navy is getting ready to test the ability of Ep…

This environment created a natural opportunity for high-power microwave technology. The same electromagnetic effects that can disable drone electronics can also interfere with the control and power-management systems used by modern boat engines and autonomous vessels. Rather than developing an entirely new weapon, Epirus adapted its existing Leonidas architecture into a maritime-focused configuration known as Leonidas H2O. [Epirus+2Defence Industry]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

The result is a system intended to engage multiple categories of threat:

• Small manned boats. [defence-industry.eu]defence-industry.euDefence IndustryEpirus launches Leonidas H2O: non-kinetic maritime…10 Apr 2025 — Named Leonidas H2O, the system offers a non-kinetic m… * Unmanned surface vessels. [defence-industry.eu]defence-industry.euDefence IndustryEpirus launches Leonidas H2O: non-kinetic maritime…10 Apr 2025 — Named Leonidas H2O, the system offers a non-kinetic m…
• Autonomous maritime attack craft.
• Conventional UAVs and drone swarms operating near ships, ports or coastal infrastructure. [Epirus+2Naval News]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

This broad target set is important because modern naval security increasingly requires protection against both airborne and surface threats simultaneously.

What Outboard-Motor Disruption Showed

The most notable evidence behind Leonidas H2O comes from testing conducted through the US Navy’s Advanced Naval Technology Exercise Coastal Trident (ANTX-CT) programme. During those demonstrations, the system was evaluated against commercially available outboard motors ranging from 40 to 90 horsepower. According to Epirus and subsequent reporting, the prototype successfully affected all tested motors at operationally relevant distances. [Epirus+2Naval News]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

The significance of these tests lies in what they reveal about the mechanism of microwave interdiction. Traditional vessel-stopping methods generally rely on:

Leonidas H2O instead attempts to attack the electronic dependencies of the vessel. Modern outboard engines contain electronic control units, ignition management systems and digital components that can be vulnerable to intense electromagnetic energy. If those systems are disrupted, the engine can cease functioning even when the vessel itself remains physically intact. [Epirus+2Defence Industry]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

The tests also demonstrated effectiveness despite operating under constraints. Epirus stated that demonstrations occurred at roughly half of the system’s potential output power and with limited waveform options, yet the system still achieved successful results against every target motor presented. [Epirus+2Naval News]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

For naval planners, this matters because the objective is often to stop a threatening craft rather than destroy it. A microwave-based effect potentially offers a means of neutralising propulsion and control systems without the collateral damage associated with missiles or naval gunfire. [Epirus]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

Why Water Creates New Opportunities for Microwave Defence

The maritime environment is not simply another location for a land-based system. Water changes how sensors, communications and electromagnetic energy behave.

Reporting on Leonidas H2O has highlighted that maritime testing explored engagement geometries unique to the sea environment. Because the water surface can influence electromagnetic propagation, operators may be able to exploit reflections and other environmental effects that do not exist in the same way on land. Some observers have noted that water-surface reflections may help extend useful engagement conditions against certain targets. [Industrievandaag]industrievandaag.nlMicrogolfwapens stoppen drones en boten in één stootMicrogolfwapens stoppen drones en boten in één stootApril 11, 2025 — 11 Apr 2025 — Leonidas H2O: hoe microgolfwapens dron…Published: April 11, 2025

Equally important is the concentration of electronic systems aboard modern small craft. Autonomous vessels, remotely piloted boats and electronically controlled engines present numerous potential points of vulnerability. In effect, maritime threats are becoming more electronic, making them increasingly relevant targets for counter-electronics weapons. [DefenseScoop]defensescoop.comepirus navy hpm microwave antx coastal tridentNavy to test Epirus high-power microwave's ability to zap…4 Apr 2024 — The Navy is getting ready to test the ability of Ep…

This does not mean every vessel becomes vulnerable to a microwave weapon, nor does it eliminate the need for conventional naval defences. Instead, it creates an additional layer that can be used before kinetic engagement becomes necessary.

How H2O Broadens Leonidas Beyond Counter-UAS

The most important contribution of Leonidas H2O is conceptual rather than technical. Earlier Leonidas variants demonstrated that high-power microwaves could defeat groups of drones. H2O demonstrates that the same architecture can address a wider category of electronically dependent systems. [Epirus]epirusinc.comEpirusEpirus Leonidas High-Power Microwave: Directed Energy…Leonidas is a solid-state, high-power HPM system, utilizing Gallium Nitrid…

This broadening occurs in three ways.

First, it expands from the air domain to the surface domain. Instead of focusing exclusively on UAVs, the system is intended to affect vessels and propulsion systems operating on the water. [Epirus]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

Second, it supports layered maritime defence. A port, harbour, warship or coastal installation may face drone swarms and autonomous boats at the same time. A common microwave architecture offers a way to address both categories using a shared technology base. [FW-MAG]fw-mag.comLEONIDAS HPM C-UxS system has successful testsEpirus, the producer of LEONIDAS, a high-power microwave (HPM) vessel motors” which h…

Third, it strengthens the argument that Leonidas is fundamentally a counter-electronics platform rather than merely a counter-drone system. The core mechanism is the disruption of electronic functionality. Drones were the original mission, but boats, motors and autonomous surface craft represent additional applications of the same principle. [Epirus+2Epirus]epirusinc.comEpirusEpirus Leonidas High-Power Microwave: Directed Energy…Leonidas is a solid-state, high-power HPM system, utilizing Gallium Nitrid…

What the Maritime Variant Suggests About Future Use

Leonidas H2O remains a prototype-stage capability, but its testing points toward several possible operational roles. These include harbour security, protection of naval vessels against unmanned surface threats, defence of coastal infrastructure and support for maritime interception missions. [Defence Industry]defence-industry.euDefence IndustryEpirus launches Leonidas H2O: non-kinetic maritime…10 Apr 2025 — Named Leonidas H2O, the system offers a non-kinetic m…

The programme also illustrates a broader trend in directed-energy development. Instead of creating separate weapons for every threat type, developers increasingly seek scalable platforms that can be adapted to different environments. H2O is an example of that approach: the same microwave technology used against drone swarms has been repackaged to confront small boats, autonomous vessels and mixed maritime-air threats. [Epirus+2Naval News]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

In that sense, Leonidas H2O is less a departure from the original Leonidas concept than an expansion of it. The maritime variant demonstrates that microwave defence can move beyond the skies and into the increasingly contested waters where autonomous systems, electronic propulsion controls and unmanned vessels are becoming central features of modern security challenges. [Epirus+2DefenseScoop]epirusinc.comEpirusEpirus Introduces Leonidas H₂O, High-Power Microwave…8 Apr 2025 — The system is built using the scalable Leonidas energy-based…

Amazon book picks

Further Reading

Books and field guides related to Can Microwave Weapons Stop Threats at Sea?. Use these as the next step if you want deeper reading beyond the article.

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The Kill Chain

By Christian Brose

Explains emerging maritime and autonomous threats.

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Army of None

By Paul Scharre

Provides broader context for autonomous maritime threats.

See on Amazon

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Naval Strategy and Operations in Narrow Seas

By Milan N. Vego

First published 2003. Subjects: Sea control, Naval strategy, Naval tactics, Defensive (military science).

See on Amazon

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Drone Wars

By Seth J. Frantzman

First published 2021. Subjects: Military art and science.

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Browse more on Amazon: The Kill Chain Army of None Naval Strategy and Operations in Narrow Seas

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Endnotes

1. Source: defensescoop.com
   Title: epirus navy hpm microwave antx coastal trident
   Link: https://defensescoop.com/2024/04/04/epirus-navy-hpm-microwave-antx-coastal-trident/
   Source snippet

   Navy to test Epirus high-power microwave's ability to zap...4 Apr 2024 — The Navy is getting ready to test the ability of Ep...

2. Source: defence-industry.eu
   Link: https://defence-industry.eu/epirus-launches-leonidas-h2o-non-kinetic-maritime-defence-system-targets-drones-and-small-boats-2/
   Source snippet

   Defence IndustryEpirus launches Leonidas H2O: non-kinetic maritime...10 Apr 2025 — Named Leonidas H2O, the system offers a non-kinetic m...

3. Source: fw-mag.com
   Link: https://www.fw-mag.com/shownews/1030/sas-2026-leonidas-hpm-c-uxs-system-has-successful-tests
   Source snippet

   LEONIDAS HPM C-UxS system has successful testsEpirus, the producer of LEONIDAS, a high-power microwave (HPM) vessel motors” which h...

4. Source: industrievandaag.nl
   Title: Microgolfwapens stoppen drones en boten in één stoot
   Link: https://industrievandaag.nl/microgolfwapens-leonidas-h2o/
   Source snippet

   Microgolfwapens stoppen drones en boten in één stootApril 11, 2025 — 11 Apr 2025 — Leonidas H2O: hoe microgolfwapens dron...

   Published: April 11, 2025

5. Source: youtube.com
   Link: https://www.youtube.com/watch?v=HQGu3GTjGAs
   Source snippet

   Epirus’ Leonidas High-Power Microwave Neutralizes 61-of-61 Drones Across 5 Flight Scenarios...

6. Source: youtube.com
   Link: https://www.youtube.com/watch?v=na0pGfopahM
   Source snippet

   Epirus Leonidas H2O maritime microwave US-made Leonidas High-Power Microwave Defeats 49-[Drone Swarm]({{ 'swarm-limits/' | relative_url }}) #airdefense UNITED24...

7. Source: epirusinc.com
   Link: https://www.epirusinc.com/press-releases/epirus-introduces-leonidas-h2o-energy-based-high-power-microwave-system-for-maritime-interdiction-and-uav-protection
   Source snippet

   EpirusEpirus Introduces Leonidas H₂O, High-Power Microwave...8 Apr 2025 — The system is built using the scalable Leonidas energy-based...

8. Source: navalnews.com
   Link: https://www.navalnews.com/event-news/sea-air-space-2025/2025/04/epirus-introduces-leonidas-h2o-high-power-microwave-system-for-maritime-interdiction-and-uav-protection/
   Source snippet

   Naval NewsEpirus Introduces Leonidas H2O, High-Power Microwave...9 Apr 2025 — The system is built using the scalable Leonidas energy-bas...

9. Source: defensenews.com
   Title: epirus debuts high power microwave weapon to knock out boat motors
   Link: https://www.defensenews.com/industry/2025/04/08/epirus-debuts-high-power-microwave-weapon-to-knock-out-boat-motors/
   Source snippet

   Epirus debuts high-power microwave weapon to knock out...8 Apr 2025 — Counter-drone company Epirus unveiled a new high-power microwave s...

10. Source: epirusinc.com
    Link: https://www.epirusinc.com/electronic-warfare
    Source snippet

    EpirusEpirus Leonidas High-Power Microwave: Directed Energy...Leonidas is a solid-state, high-power HPM system, utilizing Gallium Nitrid...

11. Source: defensedaily.com
    Title: advanced transformational technology
    Link: https://www.defensedaily.com/epirus-reveals-high-power-microwave-disables-boat-motors-used-in-navy-test/advanced-transformational-technology/
    Source snippet

    Epirus Reveals High-Power Microwave Disables Boat...14 Apr 2025 — Epirus recently unveiled the name and test results of its new prototyp...

12. Source: Wikipedia
    Title: Epirus Leonidas
    Link: https://en.wikipedia.org/wiki/Epirus_Leonidas
    Source snippet

    Epirus LeonidasThe Leonidas is a high-power microwave (HPM) weapon developed to disable unmanned aerial vehicle it has the ability to...

13. Source: wordpress-1555235-6025816.cloudwaysapps.com
    Title: epirus introduces new hpm weapon for unmanned maritime threats
    Link: https://wordpress-1555235-6025816.cloudwaysapps.com/content/epirus-introduces-new-hpm-weapon-for-unmanned-maritime-threats/
    Source snippet

    introduces new HPM weapon for unmanned...14 Apr 2025 — Epirus has unveiled a new maritime-focused high-power microwave (HPM) weapon, dub...

Additional References

1. Source: linkedin.com
   Link: https://www.linkedin.com/posts/epirus_introducing-leonidas-h%E2%82%82o-a-high-energy-activity-7315380282667204609-nkba
   Source snippet

   Leonidas H2O: a high-energy microwave system for DoDIntroducing Leonidas H₂O: a high-energy, high-power microwave system, validated in Do...

2. Source: bright.nl
   Title: dit microgolfwapen schakelt meerdere drones en boten tegelijk uit
   Link: https://www.bright.nl/nieuws/1291353/dit-microgolfwapen-schakelt-meerdere-drones-en-boten-tegelijk-uit.html
   Source snippet

   Dit microgolfwapen schakelt meerdere drones en boten...10 Apr 2025 — Het bedrijf Epirus heeft de Leonidas H2O laten zien tijdens een Ame...

3. Source: kijkmagazine.nl
   Title: nieuw microgolfwapen legt motoren van drones en boten plat
   Link: https://www.kijkmagazine.nl/tech/nieuw-microgolfwapen-legt-motoren-van-drones-en-boten-plat/
   Source snippet

   Nieuw microgolfwapen legt motoren van drones en boten...12 Apr 2025 — Het Amerikaanse bedrijf Epirus heeft een nieuw wapen ontwikkeld da...

4. Source: wesodonnell.com
   Title: the navys new secret sauce for drone
   Link: https://www.wesodonnell.com/p/the-navys-new-secret-sauce-for-drone
   Source snippet

   The Navy's New Secret Sauce for Drone Swarms...11 May 2025 — The tests, held off the California coast, targeted four different commercia...

   Published: May 2025

5. Source: youtube.com
   Title: The US Army’s new answer to drone swarms: LEONIDAS
   Link: https://www.youtube.com/watch?v=GSETxYGrxVw
   Source snippet

   How the U.S. made Leonidas high-power microwave anti-drone system could help the Philippines?...

6. Source: youtube.com
   Link: https://www.youtube.com/watch?v=SUI-l0Y8nlE
   Source snippet

   The US Army's new answer to drone swarms: LEONIDAS...

7. Source: youtube.com
   Title: Leonidas H₂O: Energy-Based HPM for Maritime Protection
   Link: https://www.youtube.com/watch?v=SQP8GoK0onc
   Source snippet

   2025's Most Terrifying Weapon Doesn’t Even Make a Sound!! Epirus Leonidas H2O...