I think it's only a matter of time before the u.s start arming s.k and Japan with nukes. China should prepare for such eventualities
the day Japan and Sk got nukes should be the day Iran has nukes as well
I think that's how China should respond
It would be a colossal own goal for the US to do that as SK and Japanese nukes will be rendered worse than useless by a single announcement from China: any use of nukes by SK or Japan will be treated as a nuclear attack by America.
That will mean the US will have to keep SK/Japanese nukes under tighter control than their own, and entirely removes the plausible deniability they so desperately crave to be able to use nukes against China without getting nuked right back in return.
In turn, you are not looking big enough for Chinese retaliation against such a move.
Nukes for Iran/Cuba are weak and ineffective responses. Instead China can and should impose excessive levels of sanctions on SK and Japan, up to and including Madeleine Albright hundreds-of-thousands-of-dead-children-is-a-price-worth-paying levels.
Such an affront to the world legal order will also be the perfect pretext for China to introduce secondary sanctions and long-arm jurisdictions itself by threatening severe sanctions on any 3rd parties that trades with SK or Japan (the inevitable America Vote at the UN against UN sanctions will give China perfect diplomatic cover). To offset the economic pain, China can push for its own semi-conductor and car exports at discount prices to affected countries while also using its vast market to absorb 3rd party exports to SK and Japan.
Even if all of that costs China money overall, it’s a price worth paying to economically obliterate America’s chief henchmen in the region and make it impossible for them to effectively contribute to America war plans against China. Hell, the economic costs to America for trying to prop the two up alone would make any economic costs to China a great investment.
China can only dream that America will be so stupid as to play such an easily countered move that will then give China a free hand to remove America’s most valuable pieces in Asia from the board without much cost or direct war.