Japan is expected to say it will study acquiring nuclear-powered submarines when it revises its three national security documents, government and ruling coalition sources have said. According to the Asahi Shimbun, the revised documents are expected to state that Japan will consider adding nuclear-powered boats to its fleet.

Talks between the ruling Liberal Democratic Party and its coalition partner, Nippon Ishin, began on 10 November. The package covers the national security, national defence and defence buildup strategies.

Study, not a decision to buy

The wording would commit the government to begin "research and studies" towards introduction, or to "consider the matter and reach a conclusion". No definitive decision to field the boats will be written into the documents, the sources said. The government will weigh the advantages, disadvantages and costs before deciding whether to proceed.

Prime Minister Sanae Takaichi ordered the review, citing China's growing maritime activity, Russia's war in Ukraine and North Korea's missile programmes. A government expert panel is due to report in early December, and the Cabinet is expected to approve the revised documents later that month.

Divisions over nuclear policy

The submarines are set to be one of the most contentious issues, alongside a possible review of the Three Non-Nuclear Principles and the defence budget. Nippon Ishin has argued Japan should acquire at least eight nuclear-powered submarines as quickly as possible, while the LDP's June proposals omitted the issue. Former Prime Minister Fumio Kishida has urged caution over costs, and former Foreign Minister Yoshimasa Hayashi has said acquiring such vessels would be difficult under the current reading of the Atomic Energy Basic Act. Ms Takaichi says the Three Non-Nuclear Principles remain policy, but has left open temporary port calls by US vessels carrying nuclear weapons in a national emergency.