Key facts
- Japan is considering investigating the acquisition of nuclear-powered submarines.
- The move is part of an upcoming update to Japan's defense strategy.
- Proponents argue nuclear submarines are essential for deterrence against Chinese military expansion.
- Conventional submarines require periodic surfacing for air intake, unlike nuclear submarines.
- Nuclear submarines can travel submerged for months and at higher speeds than conventional ones.
- Challenges include training engineers, enormous construction and operating costs, and compatibility with Japan's atomic energy basic law.
The Japanese government is contemplating the acquisition of nuclear-powered submarines as part of its ongoing review and update of its defense strategy. This consideration comes amid growing concerns over the military expansion of China into the Pacific Ocean and perceived threats from Russia.
Sources indicate that the government is considering including a proposal to study the feasibility of adopting nuclear-powered submarines within its three key security-related documents, slated for revision by the end of the year. This move is supported by proponents who argue that the extended submerged endurance, long-distance travel capabilities, and higher speeds of nuclear submarines are crucial for maintaining Japan's deterrence and response capabilities.
Conventional submarines, unlike their nuclear-powered counterparts, must periodically surface to take in air, limiting their submerged operational time. Nuclear submarines, however, can remain submerged for months at a time and travel at speeds exceeding 50 kph, compared to about 35 kph for conventional vessels. Their larger size also allows for greater armament, including counterstrike capabilities, enabling them to evade counterattacks after firing.
Despite the operational advantages, significant challenges remain. The introduction of nuclear submarines would necessitate specialized training for engineers, incur enormous construction and operating costs, and potentially conflict with Japan's atomic energy basic law, which restricts nuclear energy to peaceful purposes. Some within the ruling Liberal Democratic Party have expressed caution, with one senior lawmaker suggesting that a study might conclude they are unnecessary.
Japan currently operates a fleet of approximately 22 to 23 conventional attack submarines. The review of propulsion systems is seen as a signal to regional powers, including China, Russia, and North Korea, that Japan's traditional undersea capabilities are evolving.