02-07-2025
Japan's railgun strikes at China's hypersonic shadow
Japan's prototype ship-mounted railgun marks a bold step toward fast, affordable missile defense as it works to fill crucial gaps revealed by China's hypersonic weapons and limited interceptor supplies.
This month, The War Zone (TWZ) reported that Japan has fitted the test warship JS Asuka with a prototype electromagnetic railgun, marking a significant step toward deploying this advanced weapon system, as confirmed by recent online photos.
In June, observers spotted the railgun – similar to a previous land-based prototype developed by the Japanese Ministry of Defense's Acquisition, Technology & Logistics Agency (ATLA) – in port with its protective shroud removed, revealing internal work underway. Maritime testing is expected before the end of July.
Japan's progress contrasts with the US Navy's discontinued efforts in the early 2020s following sustained technical setbacks. The 6,200-ton Asuka accommodates containerized power systems to manage the energy demands of the railgun, which reportedly propels projectiles at Mach 6.5 using five megajoules of charge.
ATLA aims to reduce power requirements while improving barrel longevity beyond the current 120-round lifespan. The initiative aligns with future deployment plans aboard 13DDX destroyers and Maya-class vessels to bolster defenses against hypersonic threats.
Officials at the DSEI Japan 2025 defense and security equipment international forum cited continued collaboration with US counterparts and noted growing interest from France, Germany, China and Turkey in similar technologies.
Japan's railgun ambitions reflect a strategic pivot to cost-effective, rapid-fire capabilities amid intensifying regional competition.
Asia Times previously noted that the railgun's cost-effective ability to engage lower-tier threats helps reduce dependency on high-value interceptors, enabling sustained defenses against saturation missile attacks.
Underscoring China's growing missile capabilities, Maki Nakagawa notes in a March 2025 article for the Japan Institute for National Fundamentals (JINF) that China has expanded five conventional brigades equipped with DF-17 hypersonic glide vehicles (HGVs) and CJ-10/100 cruise missiles capable of striking Japan. Nakagawa highlights that the DF-17's unpredictable trajectory and the CJ-100's low-altitude, supersonic profile challenge Japan's ballistic missile defense (BMD) systems.
She adds that satellite imagery has confirmed construction at brigade-size facilities since 2018, with the 655th Brigade converted to a DF-17 unit in 2024. She states that the DF-26 intermediate-range missile, now fielded by four nuclear-capable brigades, has replaced older DF-21A units.
Japan currently employs a two-tier missile defense system, with Aegis-equipped destroyers providing midcourse interception and Patriot batteries handling terminal defense.
However, Kyodo News reported in October 2022 that Japan had only 60% of the necessary interceptor missiles for its Aegis and Patriot systems to counter threats from North Korea and China. To address the shortfall, Stars and Stripes reported in February 2025 that Japan purchased 150 SM-6 missiles worth USD 900 million from the US.
Naval News reported in April 2025 that Japan proposed co-producing SM-6 interceptors for Aegis destroyers during talks with the United States, expanding on an earlier agreement to co-produce Patriot PAC-3 missiles.
Yet, SM-6 production remains uncertain. Naval News reported in June 2025 that the US Navy's FY2026 missile procurement depended on passing a Republican-led reconciliation budget bill. The report said a funding shortfall in the proposed $817.4 million budget would trigger a contract breach, halting production after only 10 units. It added that disruption would jeopardize foreign orders from Japan, Australia, and South Korea. The bill, which had originated in the House of Representatives, passed the Senate on Tuesday.
The report warned that such a scenario would undercut allied deterrence and expose vulnerabilities in integrated air and missile defense architectures.
Former US Missile Defense Agency (MDA) director John Hill, cited by TWZ in February 2022, said that while the SM-6 is the only US interceptor theoretically capable of defeating hypersonic missiles, its capability remains 'nascent.'
Meanwhile, the successor Glide Phase Interceptor (GPI) program faces delays. Defense News reported in March 2025 that the GPI, initially scheduled for deployment by 2032, now faces a three-year delay due to early program down-selection and reduced funding, pushing delivery to at least 2035.
Andreas Schmidt, writing in Military Review in 2024, added that most hypersonic threats fly at altitudes between 20 and 60 kilometers above the reach of traditional surface-to-air missiles (SAMs) and below the coverage of exo-atmospheric interceptors like the SM-3. He argued that terminal defense systems such as Patriot are better suited for intercepting hypersonics in their terminal phase, where the weapons slow below Mach 5 and become more predictable.
However, even Patriot systems face production bottlenecks. Reuters reported in July 2024 that Mitsubishi Heavy Industries (MHI) could take years to scale up PAC-3 production due to a shortage of missile seekers supplied by Boeing. Although the report said Boeing aimed to increase output by 30% by building new production lines in the US, those lines were not expected to be operational until 2027.
Guy McCardle noted in a November 2024 SOFREP article that the limited number of Patriot interceptors per battery and their high cost – $3.7 million per missile with a production lead time of nearly 20 months – constrain their operational use. He emphasized that PAC-3 missiles must be deployed strategically to maximize their effectiveness against saturation attacks.
Given the limitations of SM-6 and Patriot systems, Japan's railgun may alleviate concerns over magazine depth and cost. Japan's Aegis warships – including four Kongo-class, two Atago-class, and two Maya-class destroyers – each carries 90 to 96 vertical launch system (VLS) cells. Yet, these may prove insufficient during a saturation attack involving hypersonic, cruise, and ballistic missiles, alongside kamikaze drones.
A railgun, integrated onto these platforms or future Aegis System Equipped Vessels (ASEVs), could significantly enhance magazine capacity.
According to a 2021 conference paper by Shreyas Maitreya and others, a 450-millimeter railgun projectile costs around $25,000, compared with missiles priced between $500,000 and $1.5 million. Unlike missiles, they note railgun rounds are inert and pose no risk of accidental detonation, easing transport and storage constraints.
Nevertheless, ATLA equipment policy division principal director Kazumi Ito acknowledged in a June 2025 National Defense Magazine article that the railgun project still faces considerable technical challenges. In the same piece, Stew Magnuson notes unresolved issues including barrel wear, energy supply, heat dissipation and development of a high-speed targeting system.
Despite these hurdles, Japan's push to operationalize railgun technology reflects a pragmatic response to a regional threat environment shaped by hypersonic proliferation, interceptor shortages and constrained missile defense capacity.
