TOKYO -- Japan plans to use underwater drones to monitor foreign submarines, seeking to ease the burdens and risks for defense personnel and enhance deterrence against China's growing fleet.

The Defense Ministry will begin research next fiscal year on mass-producing drones for detection and offensive purposes. It included this item in the fiscal 2027 budget request without specifying a funding amount.

Japanese companies will be selected for the development program that fiscal year, aiming to create prototypes by fiscal 2035.

Japan has been developing drone technology for monitoring surface vessels and aircraft. It now looks to expand its research underwater to deal with submarines.

This is intended to address China's increasingly active operations in waters surrounding Japan. China has about 60 modern submarines, nearly three times as many as Japan's Maritime Self-Defense Force. Its possession of nuclear-powered submarines increases its offensive edge beyond the fleet count.

The MSDF monitors the seas and airspace around Japan using submarines and patrol aircraft. But the current setup involves onerous long-term missions and the risk of enemy attack.

The Japanese government plans to include expanded use of unmanned vehicles in revisions to three key security documents this year. Drones, which are inexpensive and can be mass-produced, will be used to counter large submarines and other threats.

Drones are limited in the amount of equipment they can carry, making it difficult for a single drone to locate and attack a foreign submarine. Multiple drones are typically sent on such missions, with each assigned a specific role.

The new drones will share a common design for essential components, such as propellers. Only the equipment required for each mission, such as detection or torpedo launch, will be individually manufactured and replaced. This will increase operational efficiency compared with preparing separate drones for reconnaissance and attack purposes.

Common components needed for navigation can be made with the same production equipment, which reduces costs and facilitates mass production. Maintenance and procurement of replacement parts will be easier to manage. This will enable repairs to be made with mass production and long-term operation in mind. The Maritime Self-Defense Force is struggling to recruit personnel for submarine crews.

© Kyodo The Self-Defense Forces are struggling to bring in personnel. In particular, fewer people are applying to submarine crews, which must go on long deployments. The use of unmanned underwater vehicles is expected to reduce the burden on personnel.

MSDF unmanned underwater vehicles are now used primarily for mine clearance. Mitsubishi Heavy Industries has created demonstration drones with sensors and other components that can be swapped out depending on the mission.

Japanese engineering company IHI has delivered autonomous underwater vehicles to the Defense Ministry. Kawasaki Heavy Industries has technology for underwater charging.

The Ukraine and Iran wars have made heavy use of inexpensive, mass-deployable drones. Japan's revised security documents will call for accelerating development of systems for this new method of fighting.

The Defense Ministry plans to develop sensors by fiscal 2031 for small drones to detect foreign submarines. This, in conjunction with underwater drones, will enable surveillance and monitoring without human involvement.