Japan considers having nuclear-powered-sub study in security documents

The government is considering including in its three key security-related documents, slated to be revised by the end of this year, a plan to study whether the country should possess nuclear-powered submarines, government sources said Wednesday.

The move comes as proponents argue that the introduction of such underwater vessels, which can remain submerged for long periods and travel long distances, is essential for maintaining Japan’s deterrence and response capabilities as the Chinese military expands its activities into the Pacific Ocean.

In June, the junior ruling Japan Innovation Party called for the government to “swiftly introduce” nuclear submarines. The idea of introducing nuclear submarines has also been raised at a government expert panel discussing revisions to the key security documents.

Still, many in the main ruling Liberal Democratic Party remain cautious about such a step, and the government plans to make a final decision on the wording of the documents after taking into account consultations with the ruling bloc and expert panel discussions.

According to informed sources, conventional submarines must periodically raise air intake and exhaust pipes above the surface, while nuclear submarines do not need to do this and can remain submerged for several months at a time.

Nuclear submarines can also travel at speeds of more than 50 kph, compared with about 35 kph for conventional submarines. As nuclear submarines can be built larger than conventional ones, they could also be equipped with counterstrike capabilities.

“(Nuclear submarines) can quickly flee after firing in order not to be hit by a counterattack,” a senior Defense Ministry official said. “They would be highly useful.”

Nuclear submarines are not without their challenges, however. Because such underwater vessels are powered by nuclear reactors, the country would need to train and recruit engineers with specialized knowledge. Construction and operating costs would also be enormous, likely inflating defense spending.

Questions would also arise over whether nuclear submarines would be compatible with the atomic energy basic law, which limits the use of nuclear energy to peaceful purposes.

“Even if a study is conducted, the conclusion will likely be that (nuclear submarines) are unnecessary,” a senior LDP lawmaker said.