Japan’s underwater drones and hypersonic weapons anger Beijing over Taiwan contingencies

Beijing has singled out two Japanese defense plans as evidence of what it calls a dangerous military buildup: long-range missiles for unmanned underwater vehicles and hypersonic weapons testing in Australia.

Chinese Defense Ministry spokesperson Zhang Xiaogang criticized the plans on Aug. 27, describing Japan’s actions as “blatantly expanding its military capabilities” and saying they closely resembled “the militarist preparations for and launching of war before World War II.” He did not explain specifically how the two weapons programs would challenge the People’s Liberation Army.

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Blatantly expanding its military capabilities

Japan began expanding its long-range strike capabilities after adding counterstrike capabilities to its national security strategy in 2022. It has started deploying domestically developed stand-off weapons, including the Type 25 hypersonic glide vehicle that entered service in March. More advanced systems remain under development, including the Block 2 HVGP and a hypersonic cruise missile using a scramjet engine.

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The militarist preparations for and launching of war before World War II

Tokyo is also looking below the surface. A plan to study a submarine-launched hypersonic cruise missile has been reported, alongside research into technology that would allow underwater drones to fire long-range missiles. Yoshihiro Inaba, a Japan-based defense analyst with Naval News, said the Defense Ministry is developing a modular underwater vehicle for reconnaissance, submarine tracking and mine-laying. Adding long-range weapons could supplement Japan’s smaller submarine fleet and create a continuing threat to Chinese vessels around Japan’s southwestern islands or supporting a possible attack on Taiwan.

Other analysts highlighted both the potential and the limits. Timothy Heath of Perceptum said missile-equipped underwater vehicles could be quieter than submarines, difficult to track and cheap enough for mass deployment. Christopher Hughes of the University of Warwick said Japanese planners were drawing lessons from Ukraine’s use of drones and missiles against Russia’s Black Sea Fleet. Masashi Murano of the Hudson Institute cautioned that the vehicles’ size would limit their missile loads and make reloading at sea difficult. He argued that Japan’s hypersonic weapons would likely be more valuable against ships than ground targets.

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Groundbreaking

Japan’s cooperation with Australia adds another source of concern for China. Defense ministers Shinjiro Koizumi and Richard Marles agreed on Aug. 18 to let Japan use Australian test ranges over the next decade. Koizumi called the arrangement “groundbreaking,” while Marles said it would give Japan “strategic depth.” The agreement could also make Chinese intelligence collection more difficult and reflects closer political and military ties between Tokyo and Canberra, according to the analysis cited.

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Strategic depth