MELBOURNE, Australia — Japan has outlined its research and development road map for its homegrown, standoff hypersonic weapons, confirming that it is seeking an incremental growth in capability and providing more details about the kinds of threats it is targeting with this new class of weapon.

In a Japanese-language document published on the Acquisition, Technology and Logistics Agency website, the government said two classes of standoff hypersonic systems will be deployed — the Hypersonic Cruise Missile (HCM) and the Hyper Velocity Gliding Projectile (HVGP).

The former will be powered by a scramjet engine and appears similar to a typical missile, albeit one that cruises at a much higher speed while capable of traveling at long ranges.

The HVGP, on the other hand, will feature a solid-fuel rocket engine that will boost its warhead payload to a high altitude before separation, where it will then glide to its target using its altitude to maintain high velocity until impact.

The agency also provided more details regarding warhead payloads, with different warheads planned for both seaborne and land targets. The former will be an armor-piercing warhead designed specifically for penetrating “the deck of the [aircraft] carrier,” while a land-attack version will utilize a high-density, explosively formed projectile, or EFP, for area suppression.

Area suppression effects for the latter will be achieved via the use of multiple EFPs, which are more commonly known as a shaped charge. An EFP is made up of a concave metal hemispherical or cone-shaped liner backed by a high explosive, all in a steel or aluminum casing. When the high explosive is detonated, the metal liner is compressed and squeezed forward, forming a jet whose tip may travel as fast as 6 miles per second.

Japan’s road map also revealed the country is taking an incremental approach with regard to designing the shapes of warheads and developing solid-fuel engine technology, with plans to field early versions of both in the 2024 to 2028 time frame. They are expected to enter service in the early 2030s.

The agency expects both systems to navigate via satellite navigation with an inertial navigation system as backup. Japan is seeking to establish a network of seven satellites to enable continuous positioning for its self-defense forces, which will enable it to provide continuous navigation data without relying on foreign satellites.

Warhead guidance is achieved via either radio-frequency imaging converted from doppler shift data — which the government agency said will be able to identify stealthy naval targets in all weather conditions — or an infrared seeker capable to discriminating specific targets.

Japan has been conducting R&D into various areas related to hypersonic weapons for a number of years, although most of it was to benefit other fields like satellite navigation and solid-fuel rockets.

More work remains, however, in areas like hypersonic guidance systems, warhead and missile-body thermal shielding, and hypersonic propulsion systems in order for Japan to be able to field a viable standoff hypersonic weapons capability.