In early April, a ship sailed out from Yokosuka port bearing what might be the future of naval warfare. Mounted on the deck of the JS Asuka, a test ship of the Japan Maritime Self-Defense Force, was a long, boxy device that looks more like something out of a video game than a cutting-edge weapon.
But the images released by Japan’s defense ministry are very much real. The railgun is no longer a distant dream. It is crackling into life.
Last week’s sea trials mark a major leap for Japan’s defense ambitions. After nearly a decade of development, the electromagnetic railgun — a weapon that fires projectiles using magnetic fields instead of chemical explosives — is emerging as a real answer to the hypersonic threats posed by regional powers like China and Russia.
A New Kind of Gun For a New Kind of Threat
Railguns turn electrical energy into kinetic force. Using magnets, the railgun accelerates projectiles to over Mach 6 (six times the speed of sound). These projectiles unleash devastating force once the kinetic energy is released in an impact. Instead of relying on gunpowder or explosive propellants, it uses electricity to generate powerful magnetic fields between two parallel metal rails.
When a conductive projectile is placed between these rails and a current flows through it, the interaction between the magnetic field and the current produces a force. This Lorentz force rapidly accelerates the projectile down the rails and out of the barrel. So, the railgun can fire rounds at hypersonic velocities. They deliver destructive energy through sheer speed and kinetic force rather than explosive payloads.
Japan’s railgun was first tested aboard a ship in October 2023. But this latest trial involved a significantly modified version, a sign that progress is being made toward a more stable, powerful, and combat-ready system. The prototype can now fire 40mm projectiles at speeds of up to 2,000 meters per second and fire up to 120 rounds without melting its own rails. And that solves one of the biggest challenges of electromagnetic weapons — heat.
“Compared with conventional artillery, the electromagnetic gun uses a new principle to attack targets, and its attack power and accuracy are relatively high,” said Song Zhongping, a former instructor with China’s People’s Liberation Army. He also warned that the deployment of such weapons could push Japan toward a more “offensive strategy,” which may compel nations like China to make a response.
But Japan says the railgun is meant for defense, especially against the growing saturation of hypersonic and ballistic missiles from China, North Korea, and Russia. Conventional air defense uses other missiles to destroy incoming missile threats. But hypersonic missiles are very difficult — and, in some cases, impossible — to intercept.
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Why Railguns, and Why Now?
Missile-based defense systems are powerful but deeply flawed. Missiles are expensive. Some, like the American Patriot, developed by Raytheon, cost millions per shot. And warships can only carry so many of them. During recent U.S. operations in the Red Sea against the Houthis, high-end missiles were used to take down cheap drones and rockets. This is an unsustainable approach.
Japan faces the same logistical cliff. A 2022 report showed Japan had only 60% of the interceptor missiles needed for a prolonged conflict. And once a ship empties its Vertical Launch System (VLS), it has to return to port to reload, a process that can take weeks.
Railguns, by contrast, can launch smaller, non-explosive projectiles that do similar damage but cost far less. Maxwell Cooper, a retired U.S. naval officer, noted that railguns can achieve “the same lethality and accuracy” as missiles but with “greater quantities and lower cost.”
One railgun round can cost as little as $25,000, compared to several million for a missile like the SM-6. And while railgun ammunition still takes up magazine space, it doesn’t require explosive propellant, making it lighter and safer to store in bulk.
These projectiles are extremely fast — fast enough, in theory, to hit hypersonic targets. But that’s where things get tricky. Hypersonic missiles don’t follow predictable paths. They can maneuver in flight, making interception vastly harder than with traditional ballistic weapons.
To solve this, Japan’s railgun rounds will need high-tech upgrades. Guidance systems, smart sensors, and reinforced materials like tungsten will be required to survive over 30,000 g of force during launch, the kind of acceleration that would liquefy a human body.
A Technological and Strategic Gamble
Japan’s Ministry of Defense launched its railgun initiative in 2016 under the Acquisition, Technology & Logistics Agency (ATLA), investing nearly ¥50 billion (about $300 million) over the past three years. Today, it’s working with French and German research teams at the Saint-Louis Institute to refine the weapon’s capabilities.
The goal is to field a fully integrated system by fiscal year 2026, complete with improved power generation, fire control, and continuous firing capability. But major challenges remain, particularly around miniaturizing the power systems needed to support repeated firings at sea.
The United States faced similar obstacles and ultimately scrapped its railgun program in 2021. But Japan is staying the course. They are sure that railguns could solve the “missile magazine depth” problem that haunts both American and Japanese fleets.
In an age of rising geopolitical tensions and flexing militaries, railguns offer a seductive mix of power, speed, and economy. “Given China’s enormous inventory of ballistic and growing number of hypersonic missiles that can target Japan,” Timothy Heath of the RAND Corporation told SCMP, “Beijing cannot really be surprised at Japan’s determination to build such defensive systems.”
China’s former military officers have already framed Japan’s railgun as a provocation. “The threat posed to other countries and the region will be rather serious,” said Song.
For now, Japan’s railgun is still a prototype. But the sea trials signal that the country is inching closer to a fully operational system, one that might fundamentally reshape the region’s military balance.
