Ian_W
Banned
It's only possible for the Japanese to invade under conditions where there is no US embargo. They either would have had to negotiate their way out of the US' bad graces over their invasion of south Indochina or bank on their supplies holding out long enough to tackle the Soviets before attempting a move against the NEI, which, with the majority of the ground forces tied down in China and Russia would be very difficult. As said above, the US embargo of oil on Japan was the main reason why the Soviet Union did not suffer a Japanese invasion during World War II.
I dont even think its possible then, because the limited amount of Japanese foreign exchange can go into buying the oil for the Navy, or the oil for the Army to keep going in China, or the Army to fight the Soviets.
Now, fighting the Soviets is going to need quite a lot of oil for trucks alone, let alone the Navy wanting to swan around bombarding Vladivostok and otherwise wanting to look busy for the Emperor.
Finally, there is also the same issue as fighting the USA - in order for the war to end, the Japanese are going to need to be in the Kremlin dictating terms.