@Imperious:
When they took Singapore in 1941 with full strength the infantry rode on bicycles and bluffed the British into surrender. They exhausted ammo and food and other supplies just marching from Indo China. They had no idea what logistical support meant and could never sustain long lines of supplies. They were jungle fighters and not snow fighters. The land of eastern Soviets was a natural barrier. I don’t think anybody would have been in any position to support a 5-6 thousand mile long logistical train and the enemy would have easily destroyed anything to facilitate movement/ resources.
Japan had no business in Russia. It offered nothing to them except one port ( Vladivostok)
If Japan could not defeat a backward country like China that still practiced things like foot binding for all women, thats the only indication you need to qualify their abilities. China had a untrained army with no modern equipment and still Japan fights her for 14 years and gets maybe a 5th of China proper. If they attacked Russia it would take about 60 years before they made even moderate progress.
The only allies they pushed out were in Philippines, Burma, and Malaya. one of these were token defenders, and the others were pinned into a corner with no room to fight. In open country Japan would melt like ice cream in hell.
Your analysis of the Japanese Army’s backwardness is dead-on accurate. But that said, the situation in China was a tough nut for them to crack. Imagine the Vietnam War except on a much larger scale. China’s various factions used both conventional warfare and guerrilla warfare, and nothing stayed conquered unless held down by a Japanese garrison. China’s population reserves were almost unlimited, and its army was able to obtain some help from its neighbors. Outright victory in a situation like that is difficult to obtain, especially for a nation with only a fraction of China’s population size.
But as you’ve pointed out, Japan’s logistics were second- or third-rate, and its overall Army was not up to the standards of the Soviets or the Germans. To give a specific example, Japan’s main tank design was a light tank, intended to take out Chinese infantry. It was no match for a Sherman; let alone a T-34-85! To fight a war against the Soviet Union effectively, Japan would have had to make peace in China (where its army had been hopelessly bogged down), significantly increase its industrial capacity and commitment to its army. Japan produced 2,500 tanks during WWII, as compared to 105,000 for the Soviet Union. Japan produced 13,000 artillery pieces during the war, compared to 516,000 artillery pieces for the Soviets. Even apart from the logistical problems you described, those numbers don’t add up to a successful Japanese invasion of Siberia. Then there was also the problem of tactics. Japan, not having been a major participant in WWI-style trench warfare, did not appear to have learned the lessons from that war. In several instances, its soldiers would charge strongly defended American positions, much like French troops charging German machine gun emplacements in 1914. The results were the same in both cases.