Japan’s railgun takes the sting out of China’s hypersonics

Japan has fired the first ship-mounted railgun at sea, a hypersonic shot that could rewrite the balance between guns and missiles in naval warfare.

This month, Naval News reported that Japan’s Ministry of Defense (MoD), through its Acquisition, Technology & Logistics Agency (ATLA), announced the country’s first successful live firing of a ship-mounted electromagnetic railgun against a target vessel at sea, representing a potential significant turning point in Tokyo’s advanced weapons development.

The test aboard the Japan Maritime Self-Defense Force’s (JMSDF) test ship Asuka involved long-range firings and precision targeting, with ATLA releasing visual documentation via its official social media platforms.

The railgun, which uses electrical energy to launch hypervelocity projectiles—reaching speeds of nearly Mach 7—was developed to counter emerging hypersonic threats from China, North Korea and Russia.

This breakthrough follows ATLA’s earlier sea-based railgun test in October 2023 and the public exhibition of a half-scale model at DSEI Japan 2025 in Chiba Prefecture. While the technology promises rapid-fire capability and lower operational expenses compared to conventional interceptor missiles, its deployment faces challenges, notably the need for high-capacity power systems and miniaturization for integration into naval systems.

Japan’s strategic focus on railguns, high-power microwaves and laser-based systems reflects its intent to bolster missile defense capabilities amid rising regional tensions and China’s missile build-up. Further technical details are expected to be disclosed at the ATLA Technological Symposium 2025, scheduled for November in Tokyo.

Testing a railgun against a surface target could lead to a revival of naval guns, which missiles have superseded as the primary weapon in naval warfare. Railguns for surface warfare could address a longstanding overreliance on expensive anti-ship and cruise missiles to target low-end vessels or shore-based installations, thereby reserving these assets for major surface combatants or critical targets deep in enemy territory.

A ship-based railgun could fire multiple programmable rounds that simultaneously release a payload of hundreds of metal balls in a shotgun-like fashion, which could shred swarming smaller craft or suppress large-area land targets. Should precision be required, a solid projectile could be used, maximizing damage against a point target and minimizing collateral damage.

Railguns may be a cost-effective means to deal with saturation missile attacks, compared to interceptor missiles, which are priced in the millions per round. Japan’s railgun push comes as China fields DF-17 hypersonic glide vehicles (HGV) and CJ-10/100 cruise missiles capable of evading current defenses, and North Korea advances its ballistic missile program.

In terms of missile defense, railguns may be assigned terminal interception tasks. Currently, Japan employs a two-tier missile defense system consisting of Aegis-equipped destroyers for mid-course interception and Patriot for terminal interception. However, this is not a complete missile defense system.

A ballistic missile has three distinct phases of flight: boost, midcourse and terminal. The boost phase begins immediately after launch and ends when the missile leaves the Earth’s atmosphere, after its rocket motors have burned out.

While this would be the ideal phase for interception, it has a very short window of three to five minutes for intercontinental ballistic missiles (ICBMs) and even shorter—one to two minutes—for smaller missiles. A boost-phase intercept also requires interceptors to be close to launch sites, which is not ideal for Japan, given its relatively distant location from China and North Korea.

During the midcourse phase, the unpowered missile travels in a predictable ballistic arc before re-entering the Earth’s atmosphere. While this phase offers the longest time window for interception using systems such as Aegis, it also allows the missile to deploy penetration aids, including decoys, electronic warfare and multiple independently targetable reentry vehicles (MIRVs), which increase the difficulty of a successful interception. Mid-course interceptor missiles, such as the SM-3, are also scarce and costly at US$27.9 million each.

At the terminal stage, the missile or its warheads re-enter the atmosphere at hypersonic speeds, giving an interception time of less than one minute. At this stage, military bases, population centers and critical infrastructure serve as potential missile targets for point defense systems like the Patriot.

However, as with the mid-course SM-3 interceptor, Patriot interceptors are in short supply and pricey at $4 million per missile. Also, as seen in Russia’s use of the Oreshnik intermediate-range ballistic missile (IRBM) with conventional MIRVs against Ukraine, terminal defense systems such as Patriot may be ineffective against such threats.

A ship-mounted railgun may address these vulnerabilities of Japan’s missile shield, reinforcing its mid-course and terminal phase interception capabilities. Its mobility could enable it to fill in coverage gaps between Japan’s Aegis and Patriot systems.

A fast-firing, gun-based defense system could compensate for the weaknesses of missile defenses by firing numerous rounds quickly, similar to the US counter-rocket, artillery, and mortar (C-RAM) systems, but on a larger scale.

Japan is planning to build two Aegis System Equipped Vessels (ASEVs), a large destroyer design specialized for missile defense. The ASEV’s large size—190 meters in length, 25 meters in width and displacing 12,000 tons—may be necessary to accommodate 128 vertical launch system (VLS) cells.

The ASEV’s large size ties it with South Korea’s Sejong the Great destroyer, surpasses US Arleigh Burke Flight III destroyers and later-build Ticonderoga-class cruisers, which have 96 and 122 VLS cells, respectively, and exceeds China’s Type 055 cruiser, which has 112 VLS cells.

As with Japan, the US is planning to build the next-generation DDG(X) to replace its maxed-out Arleigh Burke destroyers and worn-out Ticonderoga-class cruisers, both of which no longer have the space and longevity for future upgrades such as laser weapons. In contrast with Japan’s ASEVs, later concept art of the US DDG(X) may show that the US has chosen to forgo guns in favor of additional VLS cells.

Japan’s ASEVs could provide the space needed for railgun power systems, with future iterations potentially trading their 127-millimeter main gun for electromagnetic firepower.

Still, a railgun-armed super destroyer may have significant limitations. Putting so much capability in just two ships goes against the principle of dispersion for survivability. Those ships will undoubtedly be priority targets for China or North Korea should hostilities break out between them and Japan.

Japan’s Mach-7 railgun shows that velocity, magazine depth and cost now rival range as measures of naval firepower. Whether it matures into a fleet staple or stays experimental will shape the next era of sea combat.