The AUKUS agreement effectively removes the legal taboo of the US or UK exporting 93+% weapons grade nuclear reactor HEU to Australia. By this taboo removal this trends toward legitimizing nuclear submarine propulsion for Japan.
Some senior Japanese political leaders are now talking of possible future Japanese nuclear propelled submarines quite openly.
From the late 1960s Japan completed the nuclear propelled ship Mutsu with a Japanese built miniaturized reactor. Japan has maintained a highly developed conventional sub industry and a nuclear industrial base.
Rahul Kumar, for India's daijiworld, September 28, 2021 has written an excellent commentary on the Japanese leaders'statements:
"After AUKUS, Japan debates if it too should have nuclear-powered submarines"
New Delhi, Sep 28: The AUKUS deal between the US, Australia and the UK to provide Australia with nuclear-powered submarines to take on China in the Indo-Pacific has caused rumblings in Japan.
Japanese politicians are debating whether Japan should also possess one. Japan goes to elections in November [2021] and the nuclear submarine for Australia, coupled with Chinese aggression in the region, has become a political issue.
Taro Kono - Japan's administrative reform minister, who is likely to lead the ruling party - Liberal Democratic Party (LDP), and may become the Prime Minister after Yoshihide Suga, is in favour of acquiring the submarines. In a TV debate on Sunday, he said: "As a capability, it is very important for Japan to have nuclear submarines".
Nikkei Asia reports that former internal affairs minister Sanae Takaichi endorsed the idea. Talking about the positives of owning a nuclear-powered submarine, she said that Japan would be able to travel longer with such a machine. These submarines are preferred because these are quieter, have a longer range and remain underwater for long.
Not everyone within the party endorses the idea.
Fumio Kishida, former policy chief of the LDP [and on Sept 29, 2021 appointed Leader of the LDP] feels that the country's security needs are not such that it needs to go far out from Tokyo's shores. He, therefore, does not feel the need for the Japanese Self Defence Forces to acquire a nuclear-powered submarine.
The fast-track geo-political changes in the seas around Japan has given fuel to much debate within the country.
China's rise as an aggressive economic and military power is making Tokyo uncomfortable. With frequent war cries about annexing Taiwan, Beijing has given much stress to Japan which feels that China might invade Japanese islands as well. The China factor has forced a worried Japan to rethink its military strategy.
The slow but continuous process through which China has usurped a number of reefs and islands in the South China Sea has made Japan and other countries nervous.
In the last few months Japan has been regularly highlighting Chinese aggression in the region. A white paper on defence accepted Taiwan as a separate territory from China. Tokyo has gone to the extent of saying that it will join forces with Taiwan against Chinese aggression."
Pete Comment
With Fumio Kishida likely to become Japan's next Prime Minister in November 2021 Japan may not "go nuclear sub" in the short-medium term. But AUKUS' lifting of the nuke propelled sub taboo, now appears to be permitting a trend. Previously unthinkable pro-nuclear sub statements are now being made by major Japanese politicians.