WI: Soviet Union reaches an agreement with France and Britain in 1939.

[LNSS]

There were talks about a formal alliance between these countries, but stalled because Stalin insisted on a sphere of influence over the Baltics/Finland. What if the negotiations had been successful, so when Germany invades Poland, all three powers declared war at the same time?

 

[marathag]

Well, since Molotov doesn't offer up a deal to divy up Poland with the Mustache does mean things would play out differently that September.
Without Uncle Joe on board, no way AH is going to try anything

 

[Garrison]

There were talks about a formal alliance between these countries, but stalled because Stalin insisted on a sphere of influence over the Baltics/Finland. What if the negotiations had been successful, so when Germany invades Poland, all three powers declared war at the same time?

Problem is that Stalin really wanted was for Germany, Britain and France to fight one another while the USSR stayed out. He strongly suspected that the British and French were hoping Nazi Germany and the USSR would fight to exhaustion so he turned the tables on them. He simply never imagined the country that fought for four years in WWI going under in six weeks.

Well, since Molotov doesn't offer up a deal to divy up Poland with the Mustache does mean things would play out differently that September.
Without Uncle Joe on board, no way AH is going to try anything

Well he might be tempted, I suspect his Generals will be dusting off the coup plans if he tries

 

[ObssesedNuker]

Hitler goes for it anyway. He wanted a war and this remained his best chance. The chance his generals might try to coup him is there, but they usually proved quite unwilling and inept at doing so OTL, so they may also still flinch. Poland, or at least the entirety of it west of the Vistula, still falls in the short-run. Probably the eastern half too, given the state of the Red Army in 1939, but the Germans don't have the stamina or logistics in '39 to push past the Stalin line. Without Soviet supplies and being forced into a two-front war from the very beginning, Germany's kinda fucked in the long-run as the Soviets and French are able to rearm and reform their militaries based on modern battle experience. In '41, they'll start pushing back. By '42, Soviet and French forces probably shake hands somewhere in Central/Eastern Germany, depending on the details.

Post-War, there might be some excorciation of Anglo-French right-wingers for "selling out" the Baltics, Finland, and Poland (because no way are Soviet troops going to march over Poland, spill all that blood in doing so, and not install at least a "Soviet friendly" government for their troubles), but this will be the same sort of persiflage as when modern right-wingers argue the Anglo-Americans "sold out" these regions in 1944/45 OTL.

The Balkans probably remains happily neutral and independent though.

Problem is that Stalin really wanted was for Germany, Britain and France to fight one another while the USSR stayed out. He strongly suspected that the British and French were hoping Nazi Germany and the USSR would fight to exhaustion so he turned the tables on them. He simply never imagined the country that fought for four years in WWI going under in six weeks.

That, and the Germans actually offered him the land he wanted. The British and French simply weren't able to stomach such a devil's bargain without being in desperate straights like they were later.