While I agree with you that Singapore is vulnerable to military conflicts, the risk of an A-bomb is low. Given our land size, anyone using an A-bomb will not just destroy our country, but neighbouring countries and the fishing industry as well!
Excellent analysis. You correctly pointed out that USA supported KMT, which meant that an independent China would be closely allied to the US. Alternatively, USSR supported CCP. So if China fell to communism, it would bring USSR right to Japan's doorstep!
Technically, Japan was not spreading it's ideology. It was imposing its ideology! She believed in her superiority & natural role as the leader of Asia. Spreading of ideology would be akin to what USA & USSR does during the Cold War, getting their allies to adopt political, economic & social structures that mirrors their own. Japan did no such thing for the countries they invaded.