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Türkiye Introduces THUNDERBOLT 40 mm Naval Gun Adding New Layer to NATO Close In Defense.
Türkiye’s Ermaksan has unveiled the THUNDERBOLT 40/70 T twin-barrel naval gun, a 40 mm-class system built to strengthen close-in defense against missiles, drones, and fast attack craft. The system increases a vessel’s ability to counter high-speed and multi-directional threats at short range, reinforcing survivability in contested maritime environments.
Its twin-barrel design delivers a high rate of fire and rapid target tracking, enabling engagement of multiple incoming threats in quick succession. This capability supports layered naval defense by providing a responsive inner shield against drone swarms and precision-guided munitions, reflecting broader trends in countering saturation attacks at sea.
The THUNDERBOLT 40/70 T uses twin 40 mm automatic cannons capable of reaching a combined rate of fire of up to 600 rounds per minute (Picture source: Army Recognition)
The system is displayed at SAHA EXPO 2026 in Istanbul, held from May 5, 2026, marking its first official public presentation to defense professionals. This exposure takes place in a context where Türkiye is increasing efforts to promote its naval systems internationally. Within this environment, Ermaksan positions the THUNDERBOLT 40/70 T as an alternative to existing Western systems, particularly for mid-sized navies seeking multi-role and cost-conscious point-defense solutions.
The program originates from a strategic cooperation agreement signed in June 2022, which accelerated development activities. Firing trials conducted in Karapınar in July 2025 validated the system’s ballistic performance and enabled its transition into serial production. This progression from testing to industrialization reflects a structured approach aligned with the priorities of Türkiye’s defense industrial base, which emphasizes domestic production and reduced reliance on external suppliers.
From a technical standpoint, the THUNDERBOLT 40/70 T uses twin 40 mm automatic cannons capable of reaching a combined rate of fire of up to 600 rounds per minute. This volume of fire allows engagement of fast-moving targets within short reaction windows, including anti-ship missiles in their terminal phase. The system has a maximum range of approximately 12,500 meters and a muzzle velocity of 1,000 meters per second, which improves ballistic performance and reduces time-to-target. It can carry up to 736 ready rounds, a parameter that supports sustained engagements during saturation attacks without immediate resupply.
The design also incorporates a composite dome optimized to reduce radar cross-section. By limiting electromagnetic reflections, the system contributes to overall signature management of the host vessel, reducing detectability and complicating targeting by adversary sensors. This approach reflects trends observed in NATO navies, where even secondary weapon systems are increasingly designed with low-observable features.
In comparison with equivalent systems, the THUNDERBOLT 40/70 T follows the operational logic of dual-purpose naval guns such as the DARDO 40 mm developed in Italy by OTO Melara, now part of Leonardo, and the Bofors 40 mm Mk4 designed in Sweden by BAE Systems Bofors. The DARDO, deployed on several fast vessels, also uses a twin-barrel configuration to achieve high rates of fire, but it does not incorporate specific measures to reduce radar signature. By contrast, the Bofors Mk4 emphasizes modularity, digital fire-control integration, and the use of programmable ammunition, including airburst rounds for counter-unmanned aerial system roles.
In the United States, the U.S. Navy relies on a different approach based on systems such as the Phalanx Close-In Weapon System (CIWS), a 20 mm rotary cannon developed by Raytheon, capable of exceeding 4,000 rounds per minute but with a shorter effective range typically below 2 kilometers, and the SeaRAM system, which combines a missile launcher with Phalanx-derived sensors to intercept threats at close range. This doctrinal preference prioritizes very high firing rates or missile-based interception, whereas 40 mm systems such as the THUNDERBOLT offer longer engagement distances and higher per-round impact. The Turkish system therefore occupies an intermediate position, combining rate of fire, extended range, and potential compatibility with modern ammunition types, although aspects such as full integration with fire-control radars and combat management systems remain to be independently confirmed.
Operationally, the system is designed to counter a broad range of threats at short to medium range. Its elevation envelope, from -13 degrees to +85 degrees, enables engagement of sea-skimming missiles as well as high-angle aerial targets such as helicopters or unmanned aerial vehicles. Full 360-degree azimuth coverage allows continuous engagement capability regardless of vessel maneuver. When integrated into a naval combat architecture that includes fire-control radars, electro-optical sensors, and tactical data links, such a gun forms the final layer of defense before impact. In scenarios involving drone swarms or coordinated surface attacks, the combination of high rate of fire and proximity-fuzed or programmable ammunition can disrupt or neutralize incoming threats at critical distances.
Recent operational experience has contributed to renewed interest in the 40 mm caliber. Smaller calibers may lack sufficient terminal effect, while larger systems are less suited for repeated engagements due to cost and rate-of-fire constraints. The 40 mm category offers a balance between these factors, particularly when paired with advanced ammunition designed to increase effectiveness against small or low-signature targets.
The introduction of the THUNDERBOLT 40/70 T reflects Türkiye’s intent to strengthen its naval industrial base while expanding its presence in the global defense market. By offering a domestically developed alternative to European systems, Ankara reduces exposure to export restrictions and increases flexibility in defense partnerships.
Written By Erwan Halna du Fretay - Defense Analyst, Army Recognition Group
Erwan Halna du Fretay holds a Master’s degree in International Relations and has experience studying conflicts and global arms transfers. His research interests lie in security and strategic studies, particularly the dynamics of the defense industry, the evolution of military technologies, and the strategic transformation of armed forces.