Sciencegeek – I assume the agreement you mean was the Munich Agreement (known to the Czechs as the Munich Betrayal) by which Britain recognised Hitler's annexation of the the Czech Sudentenland. Nowadays we regard that as a cowardly surrender to a blood-thirsty dictator, and Chamberlain as, at best, a foolish dupe who was taken in by Hitler's pledge that he would make no further territorial demands in Europe. It's worth pointing out though that at the time it was seen as a rather distasteful but necessary expedient which (it was believed) had prevented war, and it was greeted with immense relief.

I agree with nearly everything you say, except that I could never regard Stalinist Russia and the Third Reich as being bedfellows, despite their both being run by paranoid murderous thugs who each though of himself as a master of military strategy, and despite the huge quantities of oil, grain, and steel which Russia supplied to Germany as a condition of the pact. From the earliest beginnings of Nazism, the two ideologies had been implacable and deadly enemies. The two leaders hated each other and what each other stood for (even though, to us, what they stood for was in practice almost exactly the same). War between the two was only a matter of time, and both leaders knew that. Their non-aggression pact suited both at the time – a ghastly and short-lived marriage of convenience, and the sudden divorce was a terrific psychological shock to Stalin.

Your 5th para suggests that Japan could have sided for a short time with Nazi Germany against Russia, and postponed her attack on the US until after Russia had been knocked out. In fact, Russia and Japan had been (unofficially) at war since at least 1938, on the Manchurian border. Evidently Japan had not the strength to make a serious impression on the Red Army. No doubt Japanese planners saw that it was much more important to go for the essential supplies of oil and rice etc of SE Asia, which were much easier to get, and of course they hoped and expected to knock the USA out with their sneak attack on Pearl Harbour.

I'm not sure either that there was that much collusion or co-operation between the Axis Powers. Each had their own agenda, and often operated independently, often to the exasperation of Hitler, the Pearl Harbour attack being a case in point.

Neither am I sure that Stalin's attack on Japan was part of a pact made with the Allies, who undoubtedly would have preferred Russia to be a go-between in peace negotiations in the Pacific. As it was, the Japanese envoys to Moscow were kept dangling for some time while Stalin and the Stavka prepared their invasion of Manchuria. Russian expansion eastwards must have been an unwelcome development for the Allies, especially at that stage of the war.