At this point Japan did not have an air force or navy capable of defending the islands. Without an air force Japan could not project any power past their own beaches. The reason Germany could not invade Britain is that they failed to defeat the RAF in the Battle of Britain. One of the largest Soviet naval bases, Vladivostock, is right in the neighborhood, and had been untouched throughout the whole war.
You must be kidding ...Japan was hammer the US Navy with kamikaze attack and had over 5000 kamikaze aircraft waiting for the US invasion fleet at the end of the war
But your point is moot as the Soviet had no invasion fleet to ever try to get across TOO Japan...how you going to get thoese taks across, by rowboat?
Your not being logical...
The US could of try just a massive land force in China to battle Japan ... that would be the same thing as the Soviet had and massive land force on the mainland...
the US built the Naval force it did for Japan for a reason...but by magic the Soviet Army was going to walk across the water