Franklin Roosevelt might have looked for a justification to join Britain in a 1939 war with Japan. Isolationism is easier to sustain during peace than while a conflict is visibly changing the balance of power. British success might have looked plausible because important elements of the Japanese fleet familiar from the later Pacific War were not yet available. This remains explicit speculation about how anticipated duration and relative readiness could alter the domestic politics of intervention.
Notable Point · 30:40-31:28
Would Roosevelt enter a 1939 Pacific war?
A counterfactual suggests Roosevelt might find a reason to support Britain if a naval war with Japan appeared likely to end quickly.