Japan plans to develop an underwater-launched hypersonic guided missile as part of a broader effort to strengthen its long-range strike and undersea warfare capabilities, according to the country’s fiscal 2027 defence budget request.
The Japanese Defence Ministry included the new weapon as an unpriced item request in its latest budget plans. The ministry describes the project as the development of a stand-off weapon that can be launched from a highly survivable underwater platform and can strike at long range.
The official documents do not specify whether the eventual weapon will be launched from conventional submarines or another underwater platform. However, defence analysts cited by The Maritime Executive have identified two possible configurations.
One option would be a hypersonic ballistic missile launched vertically from an underwater platform. The other would be a hypersonic cruise missile powered by a scramjet engine and launched through a submarine’s torpedo tubes.
Both concepts would share the characteristics associated with hypersonic weapons: very high speed over long distances and the ability to manoeuvre during flight. Those characteristics can reduce an adversary’s reaction time while making the weapon more difficult to track and intercept.
The planned system would form part of Japan’s expanding stand-off strike capabilities. Tokyo is already developing and acquiring a range of long-range weapons, including submarine-launched missiles, improved Type 12 missiles and hypersonic weapons. The Defence Ministry has separately requested funding for a submarine-launched guided missile developed by Mitsubishi Heavy Industries.
Japan’s fiscal 2027 defence request totals a record 8.9 trillion yen ($55.6 billion), with increased emphasis on long-range weapons, unmanned systems, artificial intelligence and maritime capabilities.
By Tamilla Hasanova
