Japan's Missiles China Target Capable.

Japan's Type 12 surface to ship missile would need major changes to upsize it into an intermediate-range (out to 5,500km) hypersonic cruise missile. It would need to be longer, wider, with a much larger warhead to impress Chinese targets. Japan's Epsilon rocket, at the end of this Submarine Matters' article, is more capable.
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Gessler, with customary acuity, commented on September 13, 2022, along the lines: 

There is “an important development with regard to Japan's 're-armament' program:

During the ongoing 2+2 Ministerial (Defence & Foreign Ministries) dialogue between Japan & India, the Indian side has expressed its support for Japan's development of 'counter-strike' capabilities.

While the terms 'counter-strike' and 'counter-value' are invariably linked to nuclear weapons in any other context, it appears that at least so far the Japanese are only hinting at a conventional long-range strike capability with cruise missiles. The procurement in question is this. 

Keeping in mind what Pete has already written regarding Japan's capability to go nuclear in a 'long weekend', I think nobody can realistically dismiss that such a long-range strike capability, once obtained, will always remain conventionally-armed.

In my opinion, these strike missiles will be made to be nuclear-capable platforms, conventionally armed now and in the foreseeable future, but able to be mated with the nuclear warheads as and when required. 

The question now is, why the Japanese side considered it important to make this part of the agenda in the high-level meeting with Indian counterparts, and why India felt it important to pledge support for the same...This is considering the missile project (modified Type-12 ) is not a joint Japan-India program. In any event, the Japanese option of extending a force of 1,500 supersonic or hypersonic? Type 12 missiles upsized to a 1,000km range is not long enough to reach India. So there is no reason to think that the purpose of the mention was to allay any fears the Indian side may have regarding Japan's re-armament.

Could the two countries be attempting to send a signal to China that nuclear weapons-related cooperation between India & Japan is not off the table? That India would/could be willing to allow cold-testing of nukes meant for/designed by Japan to be carried out on its soil? Using its established infrastructure (which is NOT regulated/checked by anyone as India is not an NPT member)?

We are in for some interesting times ahead.

Pete Responds

The above mentioned Type 12 as a super or hyper sonic cruise missile is more difficult to shoot down than a subsonic cruise missile counter-strike against China, Russia or North Korea. Sheer flight speed makes counter-strike or even pre-emptive strike more credible.

Given the short Chinese ballistic missile flight time to Japan – Japan would be well advised to mount many of its Type 12s variants on hard to detect and hit Japanese submarines.

Japanese conventional warheads are insufficient to impress nuclear armed opponents. Conventional warheads wouldn't make much impression on ICBM silos rapidly being constructed in central-western China. Also Japan would need to preach Mutually Assured Destruction to counter China's SSBN first or second strike capability.

For a land silo force Japan's solid fuel "ICBM in waiting" Epsilon rockets may be suitable. Japan’s nuclear explosive and easily built device precursors would give Japan a "breakout" capacity of 12 months or less.

Concerning broader northeast Asian nuclear weapons proliferation - there is the illogicality of South Koreagoing to the expense of building KSS-III SSBs unless these missile submarines could be nuclear armed.

Another way of seeing things may be - secret discussions between India and Japan - which might include the possibility of India passing on Agni MRBM-ICBM technology (including thermonuclear warhead data) particularly to face the main common enemy, China.

It could be a two way barter deal with Japan passing on its (probably Minuteman III range) solid fuel Epsilon rocket technology and especially Japan's (literally) tonnes of stockpiled Plutonium could be bartered to India. Japan reputedly has 9 tonnes of Plutonium stored in Japan and 35 tonnes stored in Europe.

So there are many aspects that are unprovable without benefit of large intelligence organisation confirmation, but possible.