Originally Posted by T. A. Gardner

The Japanese did well against the US, Britain, et al., mainly for two reasons: Utilizing their superior mobility at sea and marching speed on land to out maneuver the various Allied forces they faced and in doing so turning their own doctrine against them. That is, the Allies would discover the Japanese had turned a flank on their forces that were inadequite to hold a solid line or a line anchored on what was believed "impassable" terrain.
And, the second reason was that much of the Allied forces they faced were ill-equipped, poorly trained, and often poorly led.
In the Philippines the Japanese initially landed a single reinforced division and a single brigade. The only really useful forces in the PI at that time were the Philippine Division (US Army) and Philippine Scouts (cavalry regiment). While the US had two battalions of light tanks and two of M3 halftracks with 75mm guns the US command misused these badly along with not properly supporting them logistically. The Philippine Army itself was only recently raised, very poorly trained, badly equipped (there weren't even enough rifles for every unit), and poorly led. In combat these units generally fell apart almost immediately.

In Malaysia the Japanese landed or invaded with initially 3 divisions and then added another later in the campaign. At several points the Commonwealth forces almost stopped them but then failed to do so for various reasons. Poor communications, poor training, and poor leadership at all levels led to a series of mistakes and reverses that eventually ended in the fall of Singapore.


In Burma the Japanese again used initially a single division. The same thing occured. The British would find themselves outflanked and without fully understanding the situation withdraw to form a new front only to be out flanked again.

The Dutch had the same problem. The Japanese could land almost at will and choose the time and location of their strikes. The Dutch forces were really inadequite in numbers, mobility, and leadership to deal with this and a collapse inevidably followed.

The difference against the Soviets is that there are very limited avenues of advance that have to follow the existing rail system which is very sparse in nature. Otherwise, the Japanese are realistically limited to about 200 to 300 miles from their railhead for any sustained operation. They might be able to push an extra 100 miles for temporary advances on this.
The terrain itself unlike where they fought in most of the Pacific is also not conducive to negating mechanzied force's mobility like it did elsewhere nor is it particularly conducive to infantry flanking operations. The Soviets could expect open flanks and deal with Japanese flanking thrusts by infantry with armored cars and tanks just as they did at Nomohan.
The other problem for the Japanese is the Red Army is comparatively a bottomless pit of material and manpower compared to their own. If the Soviets are losing half again the troops the Japanese are the Japanese are losing their war. For the Japanese it would still be a come as you are war and the Soviets would simply throw more units into the line. Like I said earlier, the Soviets maintained about 50 division equivalents in the Far East throughout the war while raising about 75 divisions out of this area.

The best the Japanese might hope for from a Sino-Soviet war is possibly giving Germany the edge they need to win. But, what does that buy the Japanese? Nothing. So, the question is now why would Japan engage in a war that only benefits others and has alot of risk for no return in it?