The projects were included in the defence ministry’s FY2027 budget request published at the end of August (Photo: Agencies). Japan is planning to expand its undersea strike capabilities, with the defence ministry seeking funding for submarine-based vertical launch systems (VLS) and research into a hypersonic missile that could be launched from underwater.The projects were included in the defence ministry’s FY2027 budget request published at the end of August, alongside research into a stand-off missile launch module for unmanned underwater vehicles (UUVs). The proposed investments point towards an undersea strike architecture focused on survivability, dispersed launch positions and long-range precision weapons.Japan has not disclosed the planned range, dimensions, propulsion system or warhead of the proposed underwater-launched missile.The budget request reportedly allocates approximately ¥48 billion ($325 million) to research into the underwater VLS system. A dedicated submarine VLS could allow future Japanese submarines to carry larger stand-off weapons than conventional torpedo tubes permit, while leaving those tubes available for anti-submarine and anti-surface warfare.Combining such a weapon with a concealed submarine launcher could create challenges both in locating the submarine before launch and detecting and intercepting the missile afterwards.China’s growing satellite surveillance, long-range reconnaissance capabilities, missile forces and air power could threaten fixed air bases, naval facilities and known missile positions across Japan. While land-based missile units can disperse and surface ships can manoeuvre, submarines can present a more difficult targeting problem because their locations can remain uncertain.China would potentially have to search wider maritime areas using submarines, anti-submarine warfare aircraft, surface warships and undersea sensors.The research reportedly also includes pressure-resistant launch structures, missile launch performance and submarine stability during firing.Japan’s budget proposal also includes research into a stand-off missile launch module for unmanned underwater vehicles (UUVs). Tokyo has not disclosed the UUV’s size, missile type or launch mechanism, and there is no indication that the proposed hypersonic missile itself would be carried by a UUV.However, missile-armed UUVs could eventually provide additional underwater firing positions without putting submarine crews at risk, further expanding the range of threats an opponent would have to locate.
