Japan historically moved into northern French Indochina in September 1940 while Britain closed the Burma Road under pressure. A Britain less endangered in Europe has less reason to suspend that route, so Nationalist China continues receiving outside supplies. The better-supplied Chinese war effort keeps the main body of the Japanese Army committed on the continent. Allied control of Indochina and continued British aid therefore make any southern advance a larger and more dangerous coalition war from the outset.
Notable Point · 2:22:18-2:24:16
The Burma Road stays open to China
A stronger Britain has less reason to close the Burma Road, keeping Nationalist China supplied and the Japanese Army committed there.