Japan’s Mach 5 Submarine Missile: The Stealth Strike

Tokyo earmarks $325m to develop a submarine-launched hypersonic missile capable of evading China’s surveillance.

Aryan Kumar 11 Sep 2026 ·10:12

3 min read TOKYO

Japan’s Taigei-class submarine, future launch platform for hypersonic missiles.

THE ESSENTIALS

Japan’s Ministry of Defence has requested ¥48 billion ($325 million) to study an underwater vertical launch system for hypersonic missiles.
The planned missile will travel at Mach 5, enabling strikes from submarines that are nearly undetectable while submerged.
Current Taigei-class submarines rely on 533 mm torpedo tubes, which restrict missile size and range.
China’s advanced satellites and surveillance systems threaten Japan’s land-based missile sites and naval facilities.

The Japan Maritime Self-Defense Force (JMSDF) currently relies on torpedo tubes to deploy weapons such as the Harpoon UGM-84, but these tubes impose strict size limitations on missiles. To overcome this constraint, Japan’s Ministry of Defense has earmarked ¥48 billion ($325 million) to research an underwater vertical launch system (VLS) that could accommodate larger, longer-range missiles. China’s rapid advancements in satellite surveillance, missile technology, and air forces have placed Japan’s fixed military assets, such as air bases, naval facilities, and known missile sites, at heightened risk. While land-based missile units…

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