[668 - Neighbor of the Beast]

The sheer numbers make comparisons to Japan irrelevant. How many Japanese were there in the ‘30s, maybe 100M? How many Chinese today?
Not to mention the other resources Japan lacked, and China doesn’t lack.

[TigerLikesRooster]

Unlike Japan, China has deep-rooted historical entitlement as an unparalleled hegemon. It has to virtually own all of its near-abroad and entire pacific. In time, entire world should be defacto vassals. Their current size does not make them content. Once they have enough money, they bankroll their expansionist ambition. This is so obvious to China's neighbors but probably lost among observers outside Asia, and curiously Chinese themselves.

Besides, based on China's recent frenzy to secure overseas source of necessary resources, China appears to have a different opinion. They sure lack oil. They dream for much bigger empire, which need a lot more resources to maintain.

In addition, China has not been tightly glued political entity. Disparate regions and ethnicity have always provide the strong potential for breakup. It is held together basically by brute force, with some added carrots. Maintaining the empire creates a huge overhead, without which various regions will go their own separate ways. The momentum of breakup usually starts with angry peasants. Heavy taxes, bad harvest, and corruption all provides fuel for large-scale rebellion, which ambitious people harness to advance their own ambition of becoming new hegemon. This could create long period of devastating civil war. If such a prospect become overwhelmingly likely, this would give another rationale for PLA to act on their ambition.

[Zhang Fei]

How many Japanese were there in the ‘30s, maybe 100M?

About 70m, compared to China's 600m. Japan's population is around 128m today, compared to China's 1.3b.