American entry creates a global grand alliance whose military strength comes with more complicated coalition politics. Germany and Italy have only a narrow opportunity to exploit the fleet's temporary concentration against Japan. Once a decisive battle is won, maintaining a blockade requires fewer forces and leaves the coalition able to redirect power elsewhere. An attack on one member could be treated as joining Japan against the entire alliance, so the coalition's combined strength may deter opponents before it fights them directly.
Chapter · 30:20-32:47
How a grand alliance might deter Germany and Italy
American entry strengthens the anti-Japanese coalition but also warns Germany and Italy that attacking any member could turn a regional war into a wider alliance war.