Japanese Submarine-Launched Hypersonic Missile

History

The Japanese submarine-launched hypersonic missile is a planned weapon program intended to give Japan a hypersonic strike capability from submarines. Japan's Ministry of Defense requested funding for development in the fiscal year 2027 budget, but the missile has not been publicly assigned a model designation.

The program forms part of Japan's broader expansion of long-range standoff weapons and submarine-launched strike systems. Public information does not yet identify the missile's range, propulsion system, warhead, flight profile, launch mechanism, or intended submarine class.

The new missile should not be confused with Japan's existing Hyper Velocity Gliding Projectile program or with the separate long-range cruise missiles being developed for submarine use. These programs provide technological and operational context but do not confirm the design of the FY2027 submarine-launched hypersonic weapon.

Development background

Japan has pursued hypersonic weapon technology for several years. Development of the land-based Hyper Velocity Gliding Projectile, or HVGP, began before the new submarine missile program. The HVGP uses a solid-fuel rocket booster to accelerate a glide body to high altitude before separation and high-speed flight toward its target. Japan has also been developing a separate scramjet-powered Hypersonic Cruise Missile. Details of these programs and their testing have been reported by USNI News and Breaking Defense.

In parallel, Japan began work on long-range submarine-launched conventional missiles. In October 2025, the Ministry of Defense announced contracts for mass production of an unnamed submarine-launched cruise missile and an upgraded ship-launched Type 12 missile. The submarine weapon is a separate standoff missile program and has not been confirmed as the basis of the planned hypersonic missile. Details of this effort were reported by The War Zone.

Japan is also developing a vertical launch system for future submarines. The VLS research program is scheduled to run from 2026 through 2029 with approximately 3.9 billion yen allocated for design feasibility and launch-stability verification. A disclosed concept shows seven to eight launch tubes in each module, with two or three modules potentially providing 14 to 24 cells on a submarine. Candidate weapons discussed for the system include a maritime version of the HVGP, cruise missiles, and hypersonic missiles. These details were reported by Seoul Economic Daily.

For fiscal year 2027, Japan's Ministry of Defense requested funding for development of a hypersonic missile specifically intended for submarine launch. The available reporting describes this as a new program rather than an operational weapon. Public reporting also emphasizes that its relationship to the HVGP, the Hypersonic Cruise Missile, the Type 12 family, and other submarine-launched missile projects remains unconfirmed. A summary of the reported FY2027 proposal likewise notes that the weapon's range, propulsion, warhead, flight profile, launch system, and carrier submarine have not been disclosed in public information: program summary.

Design

No detailed design of the Japanese submarine-launched hypersonic missile has been released. The available information establishes only that the weapon is intended to be launched from a submarine and to operate as a hypersonic missile.

The exact launch method remains unconfirmed. Japan is separately studying submarine vertical launch systems capable of accommodating several missile classes, including hypersonic weapons, but available evidence does not establish that the FY2027 missile will use this VLS. Japan is also developing torpedo-tube-launched long-range cruise missiles, which are a separate program.

The missile's propulsion system has not been disclosed. Japan's other hypersonic programs employ different concepts, including the boost-glide HVGP and a scramjet-powered Hypersonic Cruise Missile. There is no confirmed evidence that the planned submarine weapon will directly use either configuration.

Program status

The missile remains at the development stage. Funding was requested for fiscal year 2027, and no completed prototype, test launch, production model, or operational deployment of the exact submarine-launched hypersonic missile has been publicly identified in the supplied sources.

Development is occurring alongside Japan's efforts to improve submarine-based standoff strike capabilities. The separate VLS research program is scheduled for 2026-2029, while other Japanese hypersonic and submarine-launched missile projects are already at more advanced stages. These parallel programs may provide technology or infrastructure relevant to the new weapon, but their direct relationship to it has not been confirmed.

Specifications (planned Japanese submarine-launched hypersonic missile)

General characteristics

• Type: Planned submarine-launched hypersonic missile.
• Country of development: Japan.
• Launch platform: Submarine.
• Development status: Development funding requested for fiscal year 2027.

Performance

• Speed class: Hypersonic; the cited reporting defines hypersonic flight as exceeding Mach 5.

Related equipment

• Hyper Velocity Gliding Projectile: A separate Japanese boost-glide hypersonic weapon program. A maritime HVGP variant has been discussed as a candidate weapon for future submarine vertical launch systems, but it has not been confirmed as the FY2027 submarine-launched hypersonic missile.
• Hypersonic Cruise Missile: A separate Japanese hypersonic weapon under development using scramjet propulsion.
• Submarine vertical launch system: A Japanese development program scheduled for 2026-2029 to evaluate a multi-purpose submarine VLS capable of accommodating several missile types.
• Submarine-launched long-range cruise missile: A separate Japanese standoff weapon program for submarines, with production contracts announced in 2025.