I have seen mentioned in a couple of threads, that if there were no German invasion of the Soviet Union, that Japan would not attack the British/Dutch/USA in the Pacific. (The risk of a undistracted Soviet Union attacking Japan being too great).
Is this a true thing? It seems the advantages of Germany focusing on Britain would outweigh the risk of a Soviet attack (it is already a high risk situation anyway that Japan put itself in). (There is also the possibility of direct German-Japanese trade across the Trans-Siberian.)
The trade was more than a mere possibility. The last trainloads of natural rubber that arrived in Germany had come from Manchukuo along that rail line, in the late spring of 1941.
No, I don't think the Japanese don't attack. If anything, a neutral USSR means a relatively German-friendly USSR, and the Japanese might well think (helped in this by German diplomacy) that a new Axis is forming to possibly include the Soviets. That's unlikely in the final analysis, but a Soviet attack is just as unlikely.
So on the one hand they won't really fear a Soviet attack.
On the other hand, they really need more of that rubber. And lots of oil. And food. And other raw materials. So they are in an absurd vicious circle. They are at war in China because they wanted an empire to supply raw materials, but they find they need more raw materials to wage that war, so to get those raw materials they have to widen the war, which will burn raw materials at a much faster pace than the low-tech campaigns in China, and so on.
The only alternative is that they admit the whole "China incidents" were a big mistake and they withdraw with nothing to show for the whole venture. Otherwise, they'll seize Indochina as per OTL, and the USA will embargo what they need most, oil and scrap iron, as per OTL. Then the only alternative is go and procure those materials by making war... as per OTL.
On the plus side, note that if Germany is not knee-deep in Russian snow and German blood, then the British will be, almost by definition, busier with the Germans, and Singapore, the DEI etc. will be even less defended than in OTL.