As Chinese threat grows, Japan keeps the door open for nuclear-powered submarines

Japan has said that it is not ruling out the possibility of acquiring nuclear-powered submarines, sending out a significant signal at a time when the island nation is facing major threats from mighty neighbours such as China. The confirmation was given by the Japanese Defense Minister Shinjiro Koizumi while making a statement earlier this month.

If Japan decides to pursue the capability, it would join a small group of countries operating nuclear-powered submarines. The only nations with nuclear-powered submarines in active service are China, France, India, Russia, the United Kingdom, and the United States. Several other countries, including Australia and South Korea, are currently working to join the club.

At present, Japan operates one of the world's most capable conventional submarine fleets, which rely on advanced diesel-electric boats equipped with air-independent propulsion and advanced lithium-ion batteries. The submarines are aptly suited for operations around Japan and its surrounding waters. The Japan Maritime Self-Defense Force (JMSDF) currently operates 22 conventionally-powered submarines.


With nuclear propulsion, Japan's submarine fleets would gain much greater endurance and sustained underwater speed. This will help the Japanese navy to conduct longer-range operations across the broader Western Pacific with minimal support -- a key requirement as Japan's strategic focus expands beyond its surrounding waters. Nuclear-powered submarines are also useful for long-range surveillance, tracking, and sea-denial missions.

The pressures behind Japan’s call

One major factor forcing Japan to consider more advanced submarine capabilities is China's rapidly-expanding naval force, including a growing submarine collection and increasingly distant maritime operations. The decision also coincides with a substantial development in neighbouring South Korea, which has announced plans to develop a new class of nuclear-powered submarines.

A complex web of challenges

However, several challenges await Japan, should it pursue nuclear-powered submarines. These submarines would be far costlier than the country's current conventional boats and would require a whole new infrastructure for naval nuclear propulsion, including nuclear fuel management and specialized personnel.

There are also legal and political concerns at play. Japan’s Atomic Energy Basic Act restricts the employment of nuclear energy for peaceful purposes. This puts the development of nuclear-powered warships at odds with the existing legal mechanism. What remains to be seen is whether the Japanese government moves from keeping the option open to actually acquiring nuclear-powered submarines in the future.