Japanese submarine technology draws Australia’s attention 日本の潜水艦技術に豪州海軍が注目

The Japanese Government, at a meeting of its National Security Council (NSC) on May 18, approved transfer of the technology for the Maritime Self-Defense Force’s cutting-edge Soryu-class submarine in connection with the Royal Australian Navy’s (RAN) planned joint development of its next-generation submarine. The decision paved the way for the Australian government to choose either Japan, Germany or France as its partner in the scheme. The selection is expected to come by December.



Australian people are persistently allergic to nuclear power. That is why the country has no nuclear power stations and nuclear submarines despite being one of the world’s major uranium ore producers. The only option left to RAN is conventional submarines powered by diesel engines. Therefore, it sees Japan and Germany as potential partners because they have no nuclear submarines and have developed high technologies for conventional submarines.



Japan’s Soryu-class submarine can stay submerged below water as long as a nuclear submarine. Submarines are required to run as quietly as possible so that they may not be detected by the enemy. Soryu is also highly rated in this respect by RAN. What has made its long submergence and quiet navigation possible is a new Stirling engine, adopted for Soryu for the first time. Submarines powered by conventional diesel engines need to surface to get air. A Stirling engine based on air-independent propulsion (AIP) has done away with that necessity because it uses liquid nitrogen instead of air.


Some people in Australia say that RAN may opt for purchase of Soryu-class submarines rather than joint development. The country’s manufacturing industry has been declining as carmakers Toyota, Ford and GM Holden have decided to pull out one after another. Purchase of a foreign-made submarine means that the budget for joint development and construction is taken by the foreign country. That will not help improve Australia’s submarine technologies either. And that will be a big loss for the country’s manufacturing industry. For these reasons, many manufacturers are opposed to the purchase of Soryu. Meanwhile, some Japanese manufacturers are cautious about joint development, saying it may lead up to an outflow abroad of valuable submarine technologies.



In 2014, the Japanese government eased its three principles on arms exports and set out new three principles on transfer of defense equipment and technology. The Cabinet decisions have made it possible for Japan to jointly develop weapons with the United States and other countries with which it has cooperative relations in security. In Australia’s submarine scheme, U.S.-made weapon systems are to be adopted. So, if Soryu is chosen, it will practically become a tripartite joint development project involving Japan, Australia and the U.S. At the present stage, the matter is still at the level of joint development. However, there is the possibility of the scheme evolving into joint operation of submarines. In that sense, RAN’s upcoming selection could have some impact on the military situation in Asia.


(Written by: Takahiro Kusunoki)