Oh, I see what you are coming from. But since I've long since come to the conclusion (with the help of your arguments, no less

) that the Baku-Winter War is the most plausible PoD (apart from throwing Hitler under a bus, of course) to achive a German-Soviet alliance, I assume that alliance negotiations take place in early 1940.
The Winter War result is a co-belligerancy which leaves a whole run of issues unresolved between Russia and Germany (firstly, the Baltics; also Bulgaria, Turkey, Romania...) besides making Stalin
even more paranoid, if such a thing were possible, and calling into question whether making the capitalists fight amongst themselves is working. This, of course, is why Stalin wanted no such war and hence backed down in Finland. If it was forced on him, there's no reason to assume he'd prosecute it with much enthusiasm. His army was an even bigger mess (though a smaller force), his buffer incomplete, and he had the concern of British-guaranteed Romania down near Odessa, rather than a German-controlled Romania on the right side of the Dniestr. "Stalin a German ally" (a possible result of putting Hitler under the proverbial bus) and "Stalin a German co-belligerant" are both possible, but they're different.
By the way, let us give poor Stalin his due: the Baltic states and Bessarabia were in Soviet sphere of influence according ot M-R maps.
But Kybartai was not, and Stalin was eventually obliged to shell out some cash to compensate for grabbing it; and nothing clear had been said about Bukovina. When the Soviets entered the region, Ribbentrop objected that the whole point of the pact was to restore the old empires of the differant countries, and Bukovina had been Austrian, hence German. Molotov said "Schmeh".
But ITTL Germany doesn't mean to do Barbarossa, so it steers away from Finland and gives a greenlight about the Straits. So what is the problem ?
I think that a Germany with no intention of invading Russia could have got Russia into the Axis in 1940 (I don't think it would have lasted), but before Stalin had his buffer, he wouldn't be brought in by German diplomacy. Bringing him in by Entente attack, as I said, is a quite separate issue; and the thread does say "alliance".
But the alliance with the USSR makes the Mediterranean strategy more obvious.
Why? The USSR can't or won't help anybody to invade Britain/break her morale/starve her into submission/whatever, nor to seize Malta and Egypt. Even assuming Russia was a proper ally, the Red Army of mid-'40 has little military relevance. This was the force that had to its credit the Winter War and the "liberation march", in which largely immobile Polish home-guard held the Soviets up for far too long thanks to organisation and doctrinal chaos. It's also far away.
So the choice of whether or not to launch air attack on Britain is effectively unchanged. Now, it was always a bad choice, but they made it, thanks to the drastically different understanding of the circumstances people had a time. They didn't have the luxury of wargaming anything; they knew that Britain was in a bad way and the Germans had beaten all comers. They Germans also, ahem, knew that the RAF was considerably smaller than it was and that we would probably make peace after a good stiff bombing.
He gets to reciprocate. And he did it, to limited degrees, during WWII. After all, it's just inspection rights of the border areas.
Anything sufficient to limit his actual capacity to scheme and betray is too much. A surprise military attack on the capitalist powers was always suicide; a surprise military attack on Germany was considered seriously. (I will have none of "Suvorov's" nonsense, but Zhukov made plans, though they were never approved and probably intended as signals rather than real strategies; and I have to wonder exactly what Stalin intended to
do with that giant war machine and inter-imperialist war by 1942). If a treaty would remove Stalin's ability to do what he wants, why should he sign it? After all, he has no reason to believe Germany can attack him. His delusions about two-front warfare have no reason to have changed.
The limited, indirect benefits that OTL Germany got from destruction of the British presence in the Far East may ITTL be effectively replaced by Soviet destruction of the British presence in the Middle East, and its making a strategic threat on India. Only the latter carries no significant risk of American intervention.
By the "middle East" we mean Persia, and by "strategic threat" we mean they can hold one not huge force in place on the NWF. Feel free to elaborate on Britain's situation in your early-entry hypothetical, but assuming a late-1940 mega-axis, the situation is that we're eventually chased out of Iran and
maybe into Iraq (do remember that the Soviets were not world beaters at this point), losing us some oil; and we have to keep an observation force on the NWF, losing us some Indian troops.
The oil can come from America and the DEI. The troops are a problem but even if their loss somehow, and I don't consider it likely, is enough to get us out of Malta and Egypt and hence the whole ME and Med... what then? The convoys can just round the Cape, same as they already did.
Britain is not compelled to surrender, the Russians are still there. From Germany's perspective, a Japanese attack on the southern resource area denies Britain the DEI and its oil along with other natural resources and puts a real threat on India, and all without German exertion.
So does Stalin, short of invading Manchuria. But neither of them is bound to follow Hitler's course and rush to the side of Japan if it does the OTL gambit.
No; but Russia has rather a lot to gain, or so Stalin might think, by hostility to Japan, whereas Germany seems to have little to lose by support. And neither are they bound to have the same response. In any case, the Far East is something of a secondary question.
Make no mistake, I'm not saying that given the same basic PoD, TLs do not exist where Japan joins the Quadripartite Axis. They do. It's just that once Germany and Russia make a compact, with Italy as a sidekick, the additional strategic benefits of taking Japan onboard IMO pale in comparison to the drawbacks: much increased risk of war with America, frustration of Soviet expansion in the far East. Japan is only really useful to this Axis in the case that losing Singapore and fearing a two-front invasion of India is what it takes to bring Britain to the peace table, while they remained defiant when they lost Europe, the Mediterranean, and the Middle East. Sure, it may happen, but how often ?
I actually agree that it's not really a sound assumption that
this one more loss must necessarily force Britain (or whatever enemy it is, at any time) to give in, but it's one everybody has to make in wartime. The reality is that a nation in total war will, with rare exceptions, not keep trying to win no matter how implausible this is; and by a related principle, a victorious power unable to make the opponent give in by any previous means has got to keep trying.
Russian ambitions in the Far East were never burning. The Red Army beat Japan handily and then just left them alone until 1945 - obviously Stalin wanted his cards on the European table, and that hasn't really changed. After all, for paranoiacs, threats trump, feed, and justify ambitions and not the reverse, and so Stalin's fear of invasion from the west focuses his intentions on Europe.
I'm not saying an Anglo-Japanese alliance is impossible, either, so that one's an agree-to-disagree.
A Russia that is expanding in China is a satisfied partner that is reaping a big juicy prize and has no reason to make further claims in Europe. That is very, very much in Germany's best interest, and costs it nothing but sending some support if Stalin wants it.
Yes, it's better for Germany than for Russia; I only questioned whether it's better for Germany than an all-out, undistracted Japanese attack on Britain would be. But I do still question whether it's a good idea for the Russians. As has been pointed out, Stalin didn't want to sing "The East is Red", he wanted to keep his options open; and the Soviet-supported GMD hadn't collapsed just yet.
Balanced limitation of forces on that frontier, enforced by border inspection rights. This is pre-nuclear age, it takes months for Germany or Russia to assemble a worthy invasion force, and it is very noticeable.
That expects Germany and Russia to trust one another approximately half as far as they could throw one another, and I for one don't. Such terms weren't part of the OTL discussions to bring the USSR to the Axis, not in my knowledge.
But say they're in effect. Remember when the supplies due to Germany under the pact "went missing" just after the fall of France? Once Stalin is free from real military commitment against Britain, why not just violate the alliance seem as he several times diced with the pact. What can the Germans do about it, short of invade?
By the way, ITTL Russia has Iran, on top of its own oil resources, Germany and Italy have Arabia, either side has Iraq. What the heck would Russia need pitiful Ploesti for ??
It's a matter of Germany's supply, not Russia's. Germany having Arabia is both a stretch in real terms and a logistical head-ache - oil in Romania is a bird in your hand, oil in Arabia two in the bush. If Russia has Iran, then whoever's getting the oil from Iraq gets it at Russian suffrance.
So if the Soviets attack Romania from two sides and nab Ploesti, Germany has some oil issues.