The Japan Self-Defense Forces to Research Underwater Unmanned Vehicles in FY2027, Mass Production by 2035 to Change Anti-Submarine Surveillance

According to a report on November 1 based on an October 30 article from the Nikkei, the Ministry of Defense will begin research on underwater unmanned vehicles (UUVs) to monitor foreign submarines and other threats starting in FY2027. The plan is to complete the manufacturing and verification of prototypes by FY2035, and this research item has been included in the budget request for FY2027 without specifying an amount.

What is noteworthy about this news is not merely the increase in new unmanned equipment. The Japan Maritime Self-Defense Force currently monitors surrounding waters primarily with submarines and patrol aircraft, but long-duration patrols place a significant burden on personnel. As securing submarine crew members becomes more challenging, the idea of deploying a large number of unmanned vehicles to compensate for surveillance density is more a response to human constraints than to equipment shortages.

Common Hull and Interchangeable Payloads

The reported concept involves standardizing propulsion components such as propellers and allowing for the exchange of mission-specific devices like sonar for detection and torpedo launchers. This approach is expected to enhance procurement and maintenance efficiency compared to developing reconnaissance and attack types separately. However, as of now, details regarding range, diving depth, communication methods, and types of torpedoes have not been disclosed. Therefore, it is premature to view this as a plan to immediately replace the JMSDF's submarines.

Necessary Underwater Connectivity for the Japan-U.S. Alliance

In October, the UK Ministry of Defense announced the development of three types of sensors for AUKUS underwater unmanned vehicles: synthetic aperture sonar, deployable anti-submarine sensors, and non-maneuvering effectors, which will be available for use by the three nations' fleets starting in 2027. At the Maritime Big Play in San Diego, manned and unmanned systems are undergoing integrated testing in anti-submarine warfare, logistics, and undersea warfare.

Considering that Japan is outside the AUKUS framework, there is a gap in cooperation here. The speed at which the acoustic information collected by Japan's UUVs can be shared with the U.S. Navy's submarines, surface ships, and P-8As is more critical than the performance of the vehicles themselves. In the JMSDF's SLOC (Sea Lines of Communication) protection, the ability to reliably connect to the alliance's command and control network is what influences deterrence, rather than the ability to "detect" independently.

Challenges Remaining Before Mass Production

The concept of deploying a large number of low-cost vehicles is appealing, but in underwater environments, satellite positioning and conventional radio communications are not usable. If requirements for stealth, pressure resistance, recovery, encrypted communication, and false detection processing are not met simultaneously, increasing the number of vehicles will only add to the noise in the maritime area. Particularly when equipping with torpedo launch capabilities, how to link the unmanned vehicle's autonomous decision-making with rules of engagement becomes more a political issue than a technical one.

Source: Reference news introducing the Nikkei report (November 1, 2026), Ministry of Defense "Defense White Paper 2023," UK Ministry of Defense's AUKUS underwater sensor announcement (October 27, 2026).

According to Tanaka's view, the core of this plan is not the emergence of "unmanned submarines," but rather the redesign of the surveillance system by the JMSDF based on the premise of personnel shortages. The most overlooked risk is not mechanical failure. It is whether the different unmanned vehicles can process the incomplete contact information they gather into a unified threat perception by the Japan-U.S. command.