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News Navigator: Why are Japan's defense forces developing drone submarines?

A concept illustration of a submersible drone is seen in this image released by Japan's Defense Ministry.

The Mainichi answers some questions readers may have about the Japan's Maritime Self-Defense Force (MSDF) plan to develop submersible drones.

    Question: I heard that the MSDF is planning to develop a small unmanned submarine in the 2020 fiscal year. So, what kind of machine are we talking about?

    Answer: The MSDF has used unmanned submersibles before, to find and clear mines on the ocean's surface or the sea floor, but the drones being discussed now are different in one very important way: They would be able to attack enemy ships. The device would be tipped with a warhead, with a propulsion system in the rear.

    This is what the Defense Ministry envisions: In an emergency, the drone would be programmed and then move stealthily into a designated body of water. There it would lie in wait for vessels on their way to attack Japan. If an enemy ship were to draw near to the drone, the drone would explode like a mine and stop the ship from getting any further. Basically, they would be like mines that can self-navigate.

    Q: Would something like an AI system make all the decisions for the drone?

    A: No. The Japanese government has said it is not thinking of creating fully autonomous weapons. That being the case, the government is moving in the direction of leaving the identification of enemies and the setting off of the warhead -- that is, the decision on whether to attack -- to MSDF personnel.

    Q: Why would Japan need this kind of drone submarine?

    A: Sea mines are usually deployed by aircraft or ships. However, many countries now use observation satellites to track the military maneuvers of other nations. Using this kind of drone will preserve secrecy.

    Q: But what will all this cost?

    A: The fiscal 2020 budget sets aside 7.5 billion yen (about $71.74 million) for the construction of two prototypes. How these prototypes perform in testing, set for fiscal 2021, will determine when the drones will enter active service and how many the MSDF will have in its arsenal.

    Potential enemies are very likely to develop countermeasures against submarine drone attacks, such as deploying decoy vessels in advance of their warships. We'd like the government to take a hard look at whether there would be any point in spending the money to acquire these machines.

    (Answers by Yoshitake Matsuura, City News Department)

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