American carrier forces had broad rules of engagement if Japanese ships in unexpected waters displayed conduct that could be interpreted as aggressive intent. Congress held the constitutional power to declare war, so Roosevelt still needed to persuade legislators to support a declaration. Congressional attitudes toward Japan differed sharply from attitudes toward Germany, although individual positions varied. Many politicians treated Japan as a challenge within an American Pacific sphere of interest, an outlook strengthened after the Spanish-American War. Ernest J. King's later effort to keep British forces concentrated in the Atlantic and Mediterranean reflected that sense of American ownership of the Pacific theater.
Chapter · 0:20-5:30
Why war with Japan looked different in American politics
Broad carrier rules of engagement and congressional hostility toward Japan made a Pacific clash politically different from American intervention against Germany.