One piece of evidence that Duara uses in the passage to support his claim regarding Western racial attitudes and Japanese militarism in the second paragraph is where he says that Japan was allotted a lower quota of ships than the British and Americans.
Or you can say...
Discrimination was perceived in the international conferences in Washington (1922), the London Naval Conference (1930), and wherever Japan was allotted a lower quota of ships than the British and Americans. But most of all, it was the buildup of exclusionary policies in the United States and the final Exclusion Laws prohibiting Japanese immigration in 1924 that galled Japanese nationalists. In their view, Asian civilization did not exhibit inhuman racist attitudes and policies of this kind, and for [Japanese] militants . . . these ingrained civilizational differences would have to be fought out in a final, righteous war of the East against the West.”
One short-term effect was to shock the Allied home-populations with the surprise of a German offensive and the realization that the war was not going to be over as quickly as they had thought.
The reason why Southerners were more likely than Northerners to support the Mexican-American War is because an American victory in the war would lead to more territory in the South being gained (territory once belonging to Mexico).
